JPH0816271B2 - Plasma processing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus used for manufacturing semiconductor elements in the semiconductor industry, and particularly to the implantation of impurities into large-area semiconductor elements and semiconductor thin films. The present invention relates to a plasma processing apparatus for uniformly performing processing such as semiconductor thin film formation and etching in a short time.

2. Description of the Related Art As a method for doping a semiconductor thin film or the like with impurities in the form of ions to a desired amount and depth for doping, or for forming a thin film or etching, (1): direct current glow discharge as an ion source is used. A simple ion implanter that does not have a mass separation unit and implants ions into a semiconductor substrate or the like through an ion acceleration unit [Fig. 6, JC Muller, et al .: Proc. European Phot
ovoltaic Solar Energy Conf. (Pro seating European Photovoltic Solar Energy Conference) (Lexemberg) Sept.1977, p897-90
[Fig. 6] or (2): A DC voltage is applied to the high-frequency electrode of the plasma CVD apparatus that causes a chemical vapor phase reaction by high-frequency glow discharge by providing a capacitively coupled high-frequency electrode in the vacuum chamber. Method for superimposing voltage [7th
[Fig. 8], there is a method [Fig. 8] using a plasma processing apparatus provided with a discharge chamber configured by providing a high frequency electrode and a magnetic field generator outside the insulating cylindrical tube. In Figures 5,6,7, 1
Is a discharge chamber, 2 is a DC glow discharge anode electrode, 3 is a discharge DC power supply, 4 is an acceleration electrode, 5 is an acceleration DC power supply,
6 is a gas introduction pipe, 7 is an insulator, 8 is a gas discharge pipe, 9 is a substrate stand, 10 is a vacuum tank, 11 is a high frequency electrode, 12 is a matching box, 13 is a high frequency oscillator, 14 is a DC power supply, and 15 is a gas. Introducing pipe, 16 is a gas exhaust pipe, 17 is a sample, 20 is an insulating tubular pipe,
21 is a high frequency electrode, 22 is an electromagnet, 23 is a gas introduction tube, 24 is an insulating flange, 25-a and 25-b are direct current electrodes, 26 is a substrate chamber, 27
Is a substrate stand, 28 is a sample, and 29 is a gas exhaust pipe.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the conventional technique in which impurities are injected in the form of ions into a semiconductor thin film or the like for doping, a direct current glow discharge is used as an ion source and a mass separation unit is provided as described in (1) above. The simple ion implanter of FIG. 6 which implants impurity ions into a semiconductor substrate or the like without passing through the ion accelerating portion is operated at a pressure (1 to 0.01 Torr) that functions as an ion source to maintain a DC glow discharge. A complicated mechanism such as differential evacuation is used to maintain the pressure of the ion source and to maintain the substrate chamber at a pressure (up to 10 ^-3 Torr or less) where the mean free path of ions is more than the distance from the ion source to the substrate. In addition, if the discharge electrode is enlarged to increase the area for impurity implantation, unevenness and instability of the discharge due to creeping discharge etc. will occur, making uniform and highly accurate doping difficult. The sample is contaminated by impurities such as electrode material generated by sputtering of the discharge electrode by ions accelerated in the ion sheath region formed near the surface of the discharge electrode during high frequency discharge because it is exposed to contact ions. was there.
On the other hand, the method of applying a DC voltage to the high frequency electrode of the plasma CVD apparatus in which the capacitively coupled high frequency electrode is provided in the vacuum chamber of (2) above and causes a chemical vapor phase reaction by the high frequency glow discharge is Since the pressure in the vacuum chamber is maintained at 1 to 0.01 Torr to maintain glow discharge and the voltage that can be applied is as low as 100 to 1000 V, neutral particles other than the desired ions are deposited on the sample surface. However, it has been difficult to perform highly accurate doping of impurities by defining the concentration of impurities. Furthermore, because of the instability of the discharge due to the coincidence of the discharge electrode and the accelerating electrode, it is difficult to perform uniform doping of impurities or plasma treatment on a large-area sample. Since it is provided, there is a problem that the sample is contaminated by impurities such as electrode material generated by sputtering the discharge electrode by the ions accelerated in the ion sheath region. Further, in the method (3) of using a plasma processing apparatus using a discharge chamber having a structure in which a high-frequency electrode and a magnetic field generator are provided outside an insulating tubular tube, high-frequency power leaks to the outside,
For example, when an electromagnet is used, a current induced by a leaked high frequency flows in the electromagnet, and when the high frequency power is increased to accelerate plasma processing, the applied magnetic field becomes unstable,
Since the discharge becomes unstable and non-uniform, it is difficult to uniformly process a large area in a short time.

Means for Solving the Problems In order to solve the above problems, a plasma processing apparatus according to the present invention includes a first vacuum chamber having a surface formed of an insulating material, and an insulation between the first vacuum chamber. A high-frequency electrode provided outside the vacuum chamber along a surface formed by an object, and a conductor provided outside the high-frequency electrode, which is held at a ground potential,
Further, it is provided with a discharge chamber constituted by an electromagnet provided outside the conductor, and a substrate chamber constituted by a second vacuum chamber and a substrate stand provided therein. That is, according to the present invention, a high frequency electrode is arranged outside the vacuum chamber along the surface of the first vacuum chamber having the surface formed of the insulator, and the electromagnet is disposed outside the high frequency electrode. And a conductor provided with a ground potential between the high-frequency electrode and the electromagnet is used as an ion source, and a substrate table on which a sample to be subjected to impurity doping or plasma treatment is placed is provided in the second vacuum chamber. That is.

By configuring the vacuum chamber for generating plasma to have a surface formed of an insulating material, it is possible to provide a high-frequency glow discharge electrode outside the vacuum tank along the surface formed of the insulating material. Become. Further, by providing the high frequency electrode outside the vacuum chamber constituting the discharge chamber, ions accelerated in the ion sheath region do not sputter the high frequency electrode, which adversely affects the characteristics of the semiconductor to be doped or plasma treated. Contamination due to impurity ions and particles that can be prevented can be prevented. Further, by disposing an electromagnet, electrons are confined and a swirling motion is excited by a magnetic field applied in the discharge chamber, and the electric power supplied by the high frequency electrode is effectively used for discharging. An electromagnet or a permanent magnet is used as the magnetic field generation source. By providing a ground potential conductor between the high-frequency electrode and the electromagnet, the high-frequency power is prevented from leaking to the outside, and the current induced by the high frequency does not flow to the electromagnet, and the applied magnetic field is stable. Therefore, even if the high frequency power is increased, the discharge becomes extremely stable and uniform. Due to the above high frequency and magnetic field, stable and uniform discharge is maintained even under gas pressure of, for example, 10 ⁻³ to 10 ⁻⁴ Torr. This 10 ^-3 to 10 ^-4 Torr
The mean free path of the ions under the gas pressure of is different depending on the ion species and energy, but is the same as or more than the distance (about 10 cm) from the discharge chamber to the substrate table. Charged particles can be extruded and accelerated with a simple structure of the first conductive bias part and the second conductive bias part, and the charged particles are transported to a sample such as a semiconductor on a substrate table and irradiated to this sample. be able to. Due to the fact that the pressure inside the device can be 10 ^-3 to 10 ^-4 Torr or less and the high frequency electrode for discharge and the conductive bias part electrode for acceleration are separated, Accelerate charged particles to 1000eV or more without causing abnormal discharge such as creeping discharge and avalanche discharge. In addition, since the pressure inside the device can be set to 10 ^-3 to 10 ^-4 Torr or less, there is no deposition of neutral particles other than the desired ions on the sample surface, and highly accurate impurity doping that regulates the impurity concentration. Alternatively, plasma treatment is performed.

Examples The present invention will be described in more detail below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a first embodiment of a plasma processing apparatus according to the present invention, and FIG. 2 is a sectional view of a discharge chamber A in the first embodiment of the plasma processing apparatus according to the present invention. . The vacuum chamber 30 of the discharge chamber A is composed of a cylindrical tube made of an insulating material such as quartz, glass or ceramics. Capacitively coupled high frequency glow discharge electrodes 31-a and 31-b are made of a highly conductive metal such as copper or nickel and are provided outside the vacuum chamber 30 along the surface of the vacuum chamber 30 (see FIG. 2). . Matching box 32 for row electrode 31-a for capacitively coupled high-frequency glow discharge
A high frequency power is supplied to the vacuum chamber 30 by connecting to the high frequency oscillator 33 via a capacitor and grounding the capacitively coupled high frequency glow discharge electrode 31-b. Further, a magnetic field applied by an electromagnet 34 arranged outside the capacitively coupled high-frequency glow discharge electrodes 31-a and 31-b excites the orbital motion (electron cyclotron motion) of electrons and confine the electrons to generate a high frequency. Plasma is stably generated in the vacuum chamber 30 at a relatively low pressure of 10 ⁻³ to 10 ⁻⁴ Torr by effectively using electric power. The strength of this magnetic field may be about 20 to 200 gauss in the vacuum chamber 30 when the high frequency is 13.56 MHz. A permanent magnet may be used instead of the electromagnet. High frequency electrode 31
A conductor wall 35 made of stainless steel, aluminum, copper or the like is sandwiched between -a and 31-b and the electromagnet 34, and in this embodiment, the vacuum chamber 30 is formed by the conductor wall 35 and the insulating flanges 36-a and 36-b. A bath is formed to cover the high frequency electrodes 31-a and 30-b. The conductive mesh 37-a, which is made of conductive molybdenum, stainless steel, aluminum, titanium, tantalum, etc. and serves as the first conductive bias electrode, is made of ceramics.
It is provided in the opening 38 of the insulating flange 36-a made of Teflon, acrylic, vinyl chloride, quartz or the like. A conductive plate 37-b, which is made of conductive stainless steel, aluminum, titanium, tantalum, or the like and serves as a second conductive bias portion electrode, sandwiches the conductive mesh 37-a in the vacuum chamber 30 and the plasma 39 generated by discharge. It is provided at the opposite position. Conductor plate 37-b
Is attached to the vacuum chamber 30 via an insulating flange 36-b made of ceramics, Teflon, acrylic, vinyl chloride, quartz or the like. The conductor mesh 37-a and the conductor plate electrode 37-b are connected to a DC high voltage power supply 40, and by applying a desired voltage, the charged particles in the discharge chamber A are transferred to the substrate chamber B.
Push to accelerate. The material gas is introduced into the discharge chamber A by the gas introduction pipe 41. Substrate chamber B is a gas exhaust pipe
Connected to 42 and kept at a pressure of 10 ^-3 to 10 ^-6 Torr. A substrate table 43 made of conductive stainless steel, aluminum, copper or the like is provided in the substrate chamber B, and a sample 44 such as a semiconductor substrate is placed on the substrate table 43. The sample 44 is heated by the heater 45 to improve the efficiency of impurity doping or plasma treatment. A charged particle beam having a uniform charged particle density with respect to the opening 38 and having a kinetic energy corresponding to the potential difference between the conductor mesh 37-a and the substrate table 43, which is extracted from the plasma uniformly generated in the vacuum chamber 30. A sample 46 irradiates the sample 44 on the substrate table 43, and doping or plasma treatment of a desired amount of impurities is performed on the sample 44.

FIG. 3 is a schematic configuration diagram of a second embodiment of the plasma processing apparatus according to the present invention, and FIG. 4 is a sectional view of a discharge chamber C in the second embodiment of the plasma processing apparatus according to the present invention. . The vacuum chamber 50 of the discharge chamber C is composed of a cylindrical tube made of an insulating material such as quartz, glass or ceramics. The capacitively coupled high-frequency glow discharge electrodes 51-a and 51-b are made of a highly conductive metal such as copper or nickel and are provided outside the vacuum chamber 50 along the surface of the vacuum chamber 50. A capacitively coupled high frequency glow discharge electrode 51-a is connected to a high frequency oscillator 53 through a matching box 52 to provide a capacitively coupled high frequency glow discharge electrode.
High-frequency power is supplied to the vacuum chamber 50 by grounding 51-b. Further, due to the magnetic field applied by the electromagnet 54 arranged outside the capacitively coupled high-frequency glow discharge electrodes 51-a and 51-b, the orbital motion of electrons (electron cyclotron motion)
The plasma is stably generated in the vacuum chamber 50 at a relatively low pressure of 10 ⁻³ to 10 ⁻⁴ Torr by effectively using the high-frequency power by performing the excitation and the confinement of electrons. The strength of this magnetic field may be about 20 to 200 gauss in the vacuum chamber 50. The high-frequency electrodes 51-a and 51-b are covered with an insulator 55 such as Teflon and insulated from a mesh 56 made of conductive copper, aluminum, stainless steel or the like which is in contact with the outside (fourth).
See figure). The conductor mesh 56 is grounded and shields high frequency power. The conductive mesh 57-a, which is made of conductive molybdenum, stainless steel, aluminum, titanium, tantalum, etc. and serves as the first conductive bias portion electrode, is an insulating material made of ceramics Teflon, acrylic, vinyl chloride, quartz, etc. It is provided in the opening 59 of the flange 58. A conductive plate 57-b, which is made of conductive stainless steel, aluminum, titanium, tantalum, or the like and serves as a second conductive bias portion electrode, is sandwiched between the conductive mesh 57-a in the vacuum chamber 50 and the plasma 60 generated by discharge. It is provided at the opposite position. The conductor plate 57-b is fixed to the vacuum chamber 50 by an insulating rod 61 made of ceramics, Teflon, quartz or the like. The first conductive bias portion electrode 57-a and the conductor plate 57-b are connected to a DC high voltage power source 62, and by applying a desired voltage, the charged particles in the discharge chamber A are pushed out to the substrate chamber B and accelerated. I do. Discharge chamber C
The material gas is introduced into the chamber through the gas introduction pipe 63. The substrate chamber D is connected to the gas exhaust pipe 64 and kept at a pressure of 10 ⁻³ to 10 ⁻⁶ Torr. A substrate table 65 made of conductive stainless steel, aluminum, copper or the like is provided in the substrate chamber B.
A sample 56 such as a semiconductor substrate is placed on top. Sample 66 is heater 67
To increase the efficiency of impurity doping or plasma treatment. Plasma 60 generated uniformly in the vacuum chamber 50
With a uniform charged particle density with respect to the opening 59 and the first conductive bias portion electrode 57-a and the substrate table.
The charged particle beam 68 having a kinetic energy corresponding to the potential difference with the 65 irradiates the sample 66 on the substrate table 65, and the sample 56 is doped with a desired amount of impurities or plasma-treated.

FIG. 5 shows the plasma of nitrogen gas (N ₂ ) generated in the discharge chamber C in the second embodiment of the plasma processing apparatus according to the present invention, measured by plasma emission spectroscopy N ₂ + <0,0>:
Luminous intensity at 392 nm wavelength (RWB Bearse and AG Gaydon: T
he Identification of Molecular Spectra, (Chapman a
nd Hall, London, 1984) p227]. The emission intensity in the case without the conductor mesh 56 (I) and the case with the conductor mesh 56 (II) were set to the same high frequency power (100 W input) and magnetic field intensity (30 Gauss) and measured. The measurement place is the vacuum chamber 50 so that the five points A, B, C, D and E shown in Fig.
I went from above. The conductor plate 57-b was removed during the measurement. In the case where the conductor mesh 56 was not provided (I), the variation in emission intensity was large and the discharge was unstable. On the other hand, the inventors have found that in the case of the conductive mesh 56 (II), the variation in emission intensity is small and the discharge is stable. This is because the conductor mesh 56 at the ground potential shields the high frequency, and the current induced by the high frequency does not flow into the electromagnet, so that the magnetic field in the discharge chamber C does not change and stable and uniform plasma is generated. It indicates that As described above, using the plasma processing apparatus according to the present invention to generate stable and uniform plasma and perform uniform plasma processing, providing a ground potential conductor between the high-frequency electrode and the electromagnet has a great effect. Bring

EFFECTS OF THE INVENTION The present invention uses a vacuum chamber having a surface formed of an insulator as a discharge chamber, and by superposing a high frequency and a static magnetic field, at a relatively low pressure of 10 ⁻³ to 10 ⁻⁴ Torr, It is possible to stably generate such plasma. Further, by providing the high frequency electrode outside the vacuum chamber along the surface of the vacuum chamber, which is composed of the insulator, the ions accelerated in the ion sheath region do not sputter the high frequency electrode, so that doping or plasma is performed. Contamination by impurity ions and particles that adversely affect the characteristics of the semiconductor to be processed can be prevented, and it becomes possible to perform doping of extremely high-purity impurities or plasma processing. In addition, since the pressure inside the device can be 10 ^-3 to 10 ^-4 Torr or less and the discharge high frequency electrode and the accelerating conductive bias electrode can be separated, high pressure and DC voltage It is possible to accelerate charged particles to 1000 eV or more and to perform impurity doping or plasma treatment without causing abnormal discharges such as creeping discharges and avalanche discharges due to the high value. And since the pressure inside the device is 10 ^-3 to 10 ^-4 Torr or less, there is no deposition of neutral particles other than the desired ions on the sample surface, and highly accurate impurity doping that regulates the impurity concentration is performed. Alternatively, plasma processing can be performed. In addition, when a large-sized plasma processing apparatus is configured and is used for manufacturing a large-area element, etc., a conductor of ground potential is provided between the high-frequency electrode and the electromagnet, so that the current induced by the high frequency causes electromagnet such as electromagnet. Since it becomes possible to supply high-frequency high-frequency power without flowing into the plasma, a stable and uniform high-excitation plasma is formed by a controlled magnetic field and high-power high-frequency, and uniform plasma is generated in a short processing time. It becomes possible to perform processing. The above effects are obtained by sandwiching an insulator between the high-frequency electrode and the conductor, providing a closed container that covers the first vacuum chamber outside the electromagnet, and the substrate between the substrate chamber and the discharge chamber. A first conductive bias portion having an opening electrically connected to the chamber and the discharge chamber and connected to the first DC power source;
The first DC power supply or the second DC power supply is connected to the first DC power supply.
And a second conductive bias portion electrically isolated from the substrate chamber and the discharge chamber with a plasma generated by the discharge interposed between the second conductive bias portion and the second conductive bias portion. Providing a conductive mesh or a conductive porous plate in the opening of the first conductive bias portion,
The surface coating is provided on the side exposed to the charged particles generated by the discharge of the first conductive bias portion and the second conductive bias portion, the DC voltage is applied to the substrate table, and the substrate table is movable. A gas source is connected to the discharge chamber, a gas inlet pipe is connected to the substrate chamber, and a gas outlet pipe is connected to the discharge chamber. Connecting a gas exhaust pipe to the substrate chamber, connecting the substrate chamber to another vacuum chamber or another plasma processing apparatus through a gate valve, and connecting the substrate table to the substrate chamber and the other vacuum chamber or The same result can be obtained by adding the transportation between other plasma processing apparatuses. The plasma processing apparatus according to the present invention collectively performs high-purity impurity doping or plasma processing in the manufacture of a large-scale semiconductor device such as a long image sensor or a large-area thin film transistor array with high accuracy and uniformity in a short time. It is extremely useful in that it can be performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a plasma processing apparatus according to the present invention, FIG. 2 is a sectional view of a discharge chamber A, and FIG. 3 is a schematic of a second embodiment of the plasma processing apparatus according to the present invention. Diagram,
4 is a sectional view of the discharge chamber C, FIG. 5 is an emission intensity diagram of plasma generated in the discharge chamber C in the second embodiment of the plasma processing apparatus according to the present invention, measured by plasma emission spectroscopy, FIG. 6 is a schematic configuration diagram of a simple ion implantation apparatus that uses a direct current glow discharge as an ion source among conventional techniques and implants ions into a semiconductor substrate or the like through an ion accelerating unit without a mass separation unit, FIG. Among the conventional techniques is a schematic configuration diagram of a method of further superimposing and applying a DC voltage to the high frequency electrode of the plasma CVD apparatus in which a capacitively coupled high frequency electrode is provided in a vacuum chamber and a chemical vapor phase reaction is caused by a high frequency glow discharge, FIG. 8 is a schematic configuration diagram of a method of using a plasma processing apparatus provided with a discharge chamber configured by providing a high frequency electrode and a magnetic field generation unit outside an insulating cylindrical tube. A ... Discharge chamber, B ... Substrate chamber, 30 ... Vacuum chamber, 31-a ...
Electrodes for capacitively coupled high frequency glow discharge, 31-b ... Electrodes for capacitively coupled high frequency glow discharge, 32 ... Matching box, 33 ... High frequency oscillator, 34 ... Electromagnet, 35 ... Conductor wall, 36-a Insulating flange, 36-b Insulating flange, 37-a ... Conductor mesh, 37-b ... Conductor plate, 38 ...
… Aperture, 39 …… plasma, 40 …… DC high voltage power supply, 41…
… Gas inlet pipe, 42 …… Gas exhaust pipe, 43 …… Substrate stand, 44…
… Sample, 45… Heater, 46… Charged particle beam, C…
Discharge chamber, D ... Substrate chamber, 50 ... Vacuum chamber, 51-a ... Capacitively coupled high frequency glow discharge electrode, 51-b ... Capacitively coupled high frequency glow discharge electrode, 52 ... Matching box, 53 …… high frequency oscillator, 54 …… electromagnet, 55 …… insulator, 56 …… conductive mesh, 57-a …… conductor mesh,
57-b ... Conductor plate, 58 ... Insulation flange, 59 ... Opening, 60 ... Plasma, 61 ... DC high voltage power supply, 62 ... Insulating rod, 63 ... Gas introduction pipe, 64 ... Gas discharge Tube, 65 …… Substrate stand, 66 …… Sample, 67 …… Heater, 68 …… Charged particle beam.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01J 37/32 9508-2G H01L 21/265 21/3065

Claims (15)

[Claims] 1. A first vacuum chamber having a surface formed of an insulating material, and a high-frequency electrode provided outside the vacuum chamber along the surface of the first vacuum chamber formed of the insulating material. And a conductor provided outside the high frequency electrode, which is held at ground potential,
Further, the plasma processing is characterized by further comprising a discharge chamber constituted by a magnetic field generation source provided outside the conductor, and a substrate chamber constituted by a second vacuum chamber and a substrate stand provided therein. apparatus. 2. A plasma processing apparatus according to claim 1, wherein an insulator is sandwiched between the high frequency electrode and the conductor. 3. The plasma processing apparatus according to claim 1 or 2, further comprising a closed container which covers the first vacuum chamber outside the magnetic field generation source. 4. A first conductive bias part having an opening between the substrate chamber and the discharge chamber, the opening being electrically insulated from the substrate chamber and the discharge chamber and connected to the first DC power source. The plasma processing apparatus according to any one of claims 1 to 3, further comprising: 5. The substrate chamber and the discharge chamber are electrically connected to a first DC power source or a second DC power source by sandwiching plasma generated by discharge at a position facing the first conductive bias portion. The plasma processing apparatus according to any one of claims 1 to 4, further comprising an electrically insulated second conductive bias portion provided inside the discharge chamber. 6. The plasma according to any one of claims 1 to 5, wherein a conductive mesh or a conductive porous plate is provided in the opening of the first conductive bias portion. Processing equipment. 7. The surface coating is provided on the side exposed to the charged particles generated by the discharge of the first conductive bias portion and the second conductive bias portion. The plasma processing apparatus according to any one of item 6. 8. The plasma processing apparatus according to claim 1, wherein a DC voltage is applied to the substrate table. 9. A plasma processing apparatus according to claim 1, wherein the substrate table is movable. 10. The plasma processing apparatus according to any one of claims 1 to 9, further comprising a heating source for heating the substrate table. 11. The plasma processing apparatus according to claim 1, wherein a gas introduction pipe is connected to the discharge chamber. 12. The plasma processing apparatus according to claim 1, wherein a gas introducing pipe is connected to the substrate chamber. 13. The plasma processing apparatus according to claim 1, wherein a gas discharge pipe is connected to the discharge chamber. 14. The plasma processing apparatus according to claim 1, wherein a gas exhaust pipe is connected to the substrate chamber. 15. A substrate chamber is connected to another vacuum chamber or another plasma processing apparatus via a gate valve, and a substrate table is connected between the substrate chamber and the other vacuum chamber or another plasma processing apparatus. The plasma processing apparatus according to any one of claims 1 to 14, wherein the plasma processing apparatus transports the plasma.