JPS63157868A - Plasma treatment device - Google Patents

Abstract

PURPOSE:To generate plasma uniform in the longitudinal direction of an electrode for discharge under a low pressure so that the stable treatment of a long-sized object is permitted, by using an insulating vacuum vessel having parallel planes confronting each other and superposing a magnetic field on a high frequency. CONSTITUTION:This plasma treatment device is formed of the insulating vacuum vessel 31 which has the parallel planes confronting each other, a discharge chamber C, a high vacuum chamber of a ground potential, a movable substrate base 43 and substrate chamber D which are provided therein, and 1st and 2nd conductive bias parts 37-a, 37-b. Said discharge chamber C is constituted of a high-frequency electrode 32 and magnetic field generating source 35 provided on the outside of the vacuum vessel 31 along the above-mentioned planes confronting each other. The above-mentioned 1st bias part 37-a is insulated from the substrate chamber D and discharge chamber C and is connected to a 1st DC power supply between the substrate base 43 and the discharge chamber C. Said 2nd bias part 37-b is connected to the 1st or 2nd DC power supply.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a plasma processing apparatus used for manufacturing semiconductor devices in the semiconductor industry. The present invention relates to a plasma processing apparatus used for forming semiconductor thin films, etching, and the like.

Prior Art Methods for doping, forming or etching a semiconductor thin film by injecting impurities in the form of ions to a desired depth in the form of ions include (1): using a direct current glow discharge as an ion source; A simple ion implantation device [FIG. 3, J.

C. Muller, et al.: Proc.
European Photovoltaic 5ol
ar Energy Conf, (Proceeding European Photoportic Solar Energy Conference) (Lexenberg) 5ept,
1977, p897-909],
(2): An ion doping device that performs doping by implanting ions with a mass separation section using plasma generated by superimposing radio frequency and static magnetic fields in an insulating cylindrical tube as an ion source [Figure 4], ( 3) There is a method in which a capacitively coupled high frequency electrode is provided in the substrate chamber and a DC voltage is applied to the high frequency electrode of a plasma CVD apparatus that causes a chemical vapor phase reaction by high frequency glow discharge [FIG. 5].

In Figure 3.4.5, 1 is a discharge chamber, 2 is an anode electrode for DC glow discharge, 3 is a DC power source for discharge, 4 is an electrode for acceleration, 5 is a DC power source for acceleration, 6 is a gas introduction tube, and 7 8 is an insulator, 8 is a gas exhaust pipe, 9 is a substrate stand, A is a discharge chamber, B is a substrate chamber, 11 is an insulating film cylindrical tube, 12 is a high frequency electrode, 13 is an electromagnet, 14 is a matching box, 15 is High frequency oscillator, 16-a is a first conductive bias section, 16-b is a second conductive bias section, 17-a is a first DC power supply, 1
7-b is a second DC power supply, 18 is a gas introduction pipe, 19 is a gas discharge pipe, 20 is a substrate stand, 21 is a sample, 22 is a vacuum container, 23 is a high frequency electrode, 24 is a matching box, 25
is a high frequency oscillator, 26 is a DC power supply, 27 is a gas introduction pipe,
28 is a gas exhaust pipe, and 29 is a sample.

Problems to be Solved by the Invention In the conventional technique of doping by implanting impurities in the form of ions into a semiconductor thin film, etc., (1) an ion accelerating section that uses a DC glow discharge as an ion source and has a mass separation section; The simple ion implantation device shown in Fig. 3, which injects ions into a semiconductor substrate, etc., maintains the pressure of the ion source at a pressure (1 to O, OITorr) at which DC glow discharge occurs and functions as an ion source, and furthermore, the substrate chamber is injected into the substrate chamber. The pressure at which the mean free path of ions is greater than or equal to the distance from the ion source to the substrate (~1O-3
(torr or less), it is necessary to use differential pumping, etc., and if the discharge electrode is made large to inject impurities into a large area sample, it may cause non-uniformity and instability of the discharge due to creeping discharge of the electrode, etc. Since the discharge electrode is provided inside the ion source and is directly exposed to ions, there are problems such as contamination of the sample by impurities generated when the electrode is sputtered by ions accelerated by the self-bias of the plasma. (2) The method shown in Figure 4 uses a plasma generated by superimposing a high frequency wave and a static magnetic field in an insulating cylindrical tube as an ion source, and uses an ion doping device that performs doping by implanting ions with a mass separation section. , doping can be performed with a simple structure without the need for differential pumping, etc., because the discharge can be stably performed in a relatively large-diameter cylindrical tube, and the pressure during discharge is as low as 10-3 to 10-'torr. However, for example, if phosphorus is injected into a 3-inch single crystal silicon wafer using an insulating tube with a diameter of 13' Omm,
Sheet resistance inside the wafer after heat treatment at 00℃ for 30 minutes (
variation σ (Rs) (related to the amount of phosphorus injected)
/Rs (Rs: average value of sheet resistance, (7(R8): standard deviation of sheet resistance) is about 20%, so it is difficult to uniformly implant impurities into a large area sample. The method shown in Fig. 5 (3), in which a capacitively coupled high-frequency electrode is provided in the substrate chamber and a DC voltage is applied to the high-frequency electrode of a plasma CVD apparatus that causes a chemical vapor phase reaction by high-frequency glow discharge, is based on the method shown in FIG. The pressure is the pressure at which DC glow discharge occurs and functions as an ion source (1 to 0,01 torr).
) and that the voltage that can be applied is 100~1o.
oov and low (low), neutral particles other than the desired ions were deposited on the sample surface, making it difficult to do highly accurate impurity doping with a defined impurity concentration. Due to the instability of the discharge due to the coincidence of the accelerating electrodes, it is difficult to do extremely uniform impurity doping or plasma treatment on large-area samples.
Furthermore, since the discharge electrode is provided inside the ion source and is directly exposed to ions, there are problems such as contamination of the sample by impurities generated when the electrode is sputtered by ions accelerated by the self-bias of the plasma.

Means for Solving the Problems In order to solve the above problems, the plasma processing apparatus according to the present invention includes an insulator connected to a gas introduction pipe and formed with parallel planes facing each other with at least a predetermined area. a discharge chamber consisting of a high-frequency electrode and a magnetic field generation source provided outside the insulating vacuum chamber along opposing parallel planes of the insulating vacuum chamber; and a ground connected to a gas exhaust pipe. A substrate chamber consisting of a high-potential vacuum chamber, a movable substrate stand provided therein, and a heating source; A first conductive bias section provided in connection with a DC power supply, and a discharge generated in a position facing the first conductive bias section connected to the first DC power supply or a second DC power supply. It is provided with a second conductive bias section provided on both sides of the plasma. That is, the present invention provides an insulating vacuum chamber having at least a predetermined area of parallel planes facing each other, and an ion source located outside the insulating vacuum chamber along the facing parallel planes of the insulating vacuum chamber. A first electrically conductive bias section that extracts charged particles into the insulating vacuum chamber and accelerates them to a desired energy by disposing a high frequency electrode and further disposing a magnetic field generating source; A second conductive bias section that is pushed toward the conductive bias section side is provided at a position opposite to the first conductive bias section, sandwiching the plasma generated by the discharge, and further includes a substrate stand on which a sample to be doped with impurities or subjected to plasma treatment is placed. The idea is to make it movable.

By making the working discharge chamber an insulating vacuum chamber formed with parallel planes facing each other with at least a predetermined area, a capacitively coupled parallel plate high-frequency glow discharge electrode with which discharge is uniform over a large area can be installed in the vacuum chamber. By drawing charged particles etc. into the substrate chamber from the uniform plasma obtained in the long direction of this high frequency electrode, it is possible to provide uniform impurity particles in the long direction of the electrode. Perform doping or plasma treatment. Furthermore, by making the substrate table on which the sample is mounted movable, for example, by moving the substrate table perpendicularly to the longitudinal direction of the irradiated surface of the charged particle beam, uniform doping of impurities or plasma over a large area can be achieved. Perform processing. In addition, by providing a high-frequency electrode outside the insulating vacuum chamber, ions accelerated by the self-bias of the plasma will not sputter the high-frequency electrode, thereby preventing contamination by impurity ions such as metals generated by sputtering of the high-frequency electrode. Furthermore, by arranging a magnetic field generation source, the magnetic field applied in the discharge chamber confines electrons and excites their swirling motion, effectively using the energy supplied by high frequency to generate, for example, IQ-3 to 10-'torr. Stably and uniformly discharges even at a gas pressure of This 10-3~10-'
Although the mean free path of ions under torr gas pressure differs depending on the ion species, the first conductive path placed in the discharge chamber is equivalent to or longer than the distance from the discharge chamber to the substrate stand (approximately 10 cm). A simple structure consisting of a bias section and a second conductive bias section pushes out and accelerates charged particles, transports the charged particles to a sample such as a semiconductor on a substrate stage, and irradiates the sample. Furthermore, the pressure inside the device is 10
-3 to 10 torr or less, and because the high-frequency electrode for discharge and the conductive bias electrode for acceleration are separated, creeping discharge or avalanche discharge due to high pressure or voltage may occur. Do not cause abnormal discharge (,
Further, charged particles are accelerated to 1 keV or more without causing instability of discharge due to coincidence of the discharge electrode and the accelerating electrode. Since the pressure inside the device is below 10-3 to 10-'torr, there is no deposition of neutral particles other than desired ions on the sample surface, and highly accurate impurity doping with a specified impurity concentration is possible. performs plasma treatment.

EXAMPLES The present invention will be explained in more detail below based on the drawings.

FIG. 1 shows a schematic diagram of a first embodiment of a plasma processing apparatus according to the present invention. In this example,
An insulating rectangular tube is used as the insulating vacuum chamber having parallel planes facing each other over at least a predetermined area. The insulating rectangular tube 31 of the discharge chamber C is made of ceramics, quartz glass, etc., and the capacitively coupled parallel plate high-frequency glow discharge electrode 32 is made of a highly conductive metal such as copper or nickel. Provided outside. One of the capacitively coupled parallel plate high frequency glow discharge electrodes 32 is connected to a high frequency oscillator 34 via a matching box 33, and the other is grounded to supply high frequency power into the insulating rectangular tube 31. Furthermore, by exciting and confining the swirling motion (cyclotron motion) of electrons by the magnetic field applied by the electromagnet 35 disposed outside the capacitively coupled parallel plate high-frequency glow discharge electrode 32, relatively low pressure (IQ-3
Plasma is stably generated within the insulating rectangular tube 31 by effectively using high frequency power for discharge at a pressure of 10-' torr. The strength of this magnetic field is the insulating rectangular tube 3
The magnetic field may be about 50 to 200 Gauss within 1, and a permanent magnet or the like may be used as the magnetic field generation source. A first conductive bias section 37-a made of conductive stainless steel, aluminum, copper, etc. and having an opening 36 is connected to the discharge chamber C via an insulating flange 38 made of ceramics, quartz glass, vinyl chloride, etc. and the board chamber. The material gas is introduced into the discharge chamber C through a gas introduction pipe 39 and then through an insulating rectangular pipe 31.
The gas inlet 40 of the second conductive bias section 37-b is provided at a position opposite to the first conductive bias section 37-a. The first conductive bias section 37-a
The second conductive bias section 37-b is connected to DC high voltage power supplies 41-a and 41-b, respectively, and by applying a desired voltage, charges particles in the discharge chamber C are pushed out to the substrate chamber. Perform acceleration. The substrate chamber is connected to a gas exhaust pipe 42 and maintained at a pressure of 10-' to 10-' torr.

A movable substrate stand 43 made of conductive stainless steel, aluminum, copper, etc. is provided in the substrate chamber, and a sample 44 such as a semiconductor substrate is placed on the substrate stand 43. Sample 44 is heater 4
5 to increase the efficiency of impurity doping or plasma treatment. The longitudinal direction (second
(see figure), and uniformly in the longitudinal direction of the opening 36 (see figure 2), depending on the potential difference between the first conductive bias section 37-a and the substrate pedestal 43. The charged particle beam 46 that has obtained kinetic energy is irradiated onto a sample 44 such as a semiconductor substrate on a substrate table 43, and the sample 44 is doped with a desired amount of impurities or subjected to plasma treatment. Furthermore, by scanning the substrate table 43 perpendicularly to the longitudinal direction of the irradiated surface of the charged particle beam 46, extremely uniform impurity doping or plasma treatment is performed on a large-area sample.

FIG. 2 shows an external appearance and a perspective schematic diagram of a second embodiment of the plasma processing apparatus according to the present invention. In this embodiment as well, an insulating rectangular tube is used as the insulating vacuum chamber having parallel planes facing each other over at least a predetermined area. Discharge chamber C composed of an insulating rectangular tube 31
Inside, capacitively coupled parallel plate high frequency glow discharge electrode 3
A uniform plasma is stably generated in the longitudinal direction of the capacitively coupled parallel plate high frequency glow discharge electrode 32 under a pressure of 10-8 to 10-'torr by the high-frequency power and static magnetic field applied by the electromagnet 2 and the electromagnet 35. let A first conductive bias section 37-a to which a DC voltage is applied from this plasma.
The capacitively coupled parallel plate high frequency glow discharge electrode 32 is elongated in the longitudinal direction (from the opening 36 of the first conductive bias section 37-a provided) by the second conductive bias section 37-b. A sample 44 such as a semiconductor substrate on a movable substrate table 43 in the substrate chamber is doped with a desired amount of impurities or subjected to plasma treatment.Furthermore, the substrate table 43 is charged. By scanning perpendicularly to the longitudinal direction of the irradiation surface of the particle beam 46,
Extremely uniform impurity doping or plasma treatment is performed on a large-area sample. The material gas is introduced into the discharge chamber C through the gas introduction pipe 39, and the first conductive bias section 37-
a is fixed to the substrate chamber via an insulating flange 38. Further, the substrate chamber is connected to the second chamber via the gate valve 50.
The substrate table 43 is connected to the second vacuum chamber E, and the substrate table 43 is transported between the second vacuum chamber E and the substrate table 43, thereby performing pre-treatment and post-treatment such as doping of impurities or plasma treatment on the sample 44, and the substrate table 43. To carry out loading and unloading, etc., without breaking the vacuum in the discharge chamber C and the substrate chamber.

Effects of the Invention The present invention uses an insulating vacuum chamber formed with parallel planes facing each other with at least a predetermined area as a discharge chamber, and superimposes a high frequency and a static magnetic field to generate a discharge time of 10-s to
It becomes possible to stably generate uniform plasma in the longitudinal direction of the high-frequency glow discharge electrode under a relatively low pressure of 10-4 torr.

In addition, a very uniform charged particle beam from a uniform plasma is irradiated onto a sample such as a semiconductor substrate, and the substrate table on which the sample is placed is scanned perpendicular to the longitudinal direction of the charged particle beam irradiation surface. This makes it possible to extremely uniformly dope impurities or perform plasma treatment on a large-area sample. Furthermore, by providing a high-frequency electrode outside the discharge chamber, ions accelerated by the self-bias of the plasma will no longer sputter the high-frequency electrode, thereby eliminating contamination by impurity ions such as metals generated when the high-frequency electrode is sputtered. It becomes possible to perform high-purity impurity doping or plasma treatment.

Since the pressure is less than 10-3 to 10-'torr, there is no deposition of neutral particles other than desired ions on the sample surface, and highly accurate impurity doping or plasma treatment with a specified impurity concentration is possible. It becomes possible to do this. The above effects are achieved by connecting the gas inlet tube to the substrate chamber, connecting the gas exhaust tube to the discharge chamber, and reducing the charged particles generated by the discharge of the first conductive bias section and the second conductive bias section. A partition wall or surface coating is provided on the exposed side, the substrate chamber is connected to a second vacuum chamber or a second plasma processing apparatus via a gate valve, and the substrate table is connected to the substrate chamber and the second plasma processing apparatus.
It can also be obtained in the same way by transporting the plasma between the vacuum chamber of the second plasma processing apparatus or the second plasma processing apparatus. The plasma processing apparatus according to the present invention can perform high-purity impurity doping or plasma processing, etc., all at once with high precision, for example, in the manufacture of large-scale semiconductor devices such as long image sensors and large-area thin film transistor arrays. It is extremely useful in that it becomes possible.

[BRIEF DESCRIPTION OF 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 an external appearance and perspective schematic diagram of a second embodiment of a plasma processing apparatus according to the present invention. , Figure 3 is a schematic configuration diagram of a simple ion implantation apparatus using a conventional technique that uses DC glow discharge as an ion source and has a mass separation section. , Figure 4 shows a conventional ion doping device that uses plasma generated by superimposing high frequency waves and static magnetic fields in an insulating cylindrical tube as an ion source to inject and dope ions with a mass separation section. A schematic diagram of the configuration, Figure 5 is a schematic diagram of a conventional method of applying a DC voltage to the high-frequency electrode of a plasma CVD apparatus in which a capacitively coupled high-frequency electrode is provided in the substrate chamber and a chemical vapor phase reaction is caused by high-frequency glow discharge. FIG. C...Discharge chamber, D...Substrate chamber, 31...Insulating rectangular tube, 32...Capacitively coupled parallel plate high frequency glow discharge electrode, 33...Matching box, 34... High frequency oscillator, 35... Electromagnet, 36... Opening, 3
7-a...first conductive bias section, 37-b...
Second conductive bias portion, 38... Insulating flange, 3
9... Gas introduction pipe, 40... Gas introduction port, 41-a
...DC high voltage power supply, 41-b...DC high voltage power supply, 42...Gas exhaust pipe, 43...Board stand, 44...
- Sample, 45... Heater, 46... Charged particle beam, E... Vacuum chamber, 50... Gate valve. Name of agent: Patent attorney Toshio Nakao 1 person Figure 1 α "a h 45 Heater Figure 2 C discharge chamber Figure 3 Figure 4 Figure 5

Claims (5)

[Claims] (1) An insulating vacuum chamber connected to a gas introduction pipe and formed with parallel planes facing each other with at least a predetermined area; A discharge chamber consisting of a high-frequency electrode and a magnetic field generation source installed outside the chamber, a high vacuum chamber at ground potential connected to a gas exhaust pipe, and a movable substrate stand and heating source installed inside the chamber. a first electrically conductive bias section and a first DC power source that are insulated from the substrate chamber, the substrate chamber, and the discharge chamber and are connected to a first DC power source between the substrate stand and the discharge chamber; Alternatively, a plasma characterized by comprising a second conductive bias section connected to a second DC power source and provided at a position facing the first conductive bias section, sandwiching the plasma generated by the discharge. Processing equipment. (2) The plasma processing apparatus according to claim 1, characterized in that a gas introduction pipe is connected to the substrate chamber. (3) The plasma processing apparatus according to claim 1 or 2, characterized in that a gas exhaust pipe is connected to the discharge chamber. (4) A partition wall or a surface coating is provided on the side of the first conductive bias section and the second conductive bias section exposed to charged particles generated by discharge. Or the plasma processing apparatus according to item 2 or 3. (5) Connect the substrate chamber to a second vacuum chamber or second plasma processing apparatus via a gate valve, and connect the substrate table between the substrate chamber and the second vacuum chamber or second plasma processing apparatus. The plasma processing apparatus according to claim 1, 2, 3, or 4, characterized in that the plasma processing apparatus is transported.