CN102021524B - Device for separating ions with different masses in plasma immersion ion implantation - Google Patents

Abstract

The invention discloses a device for separating ions with different masses in plasma immersion ion implantation, which comprises a spherical cavity, a substrate table, a high-frequency electric field in the spherical cavity and a constant magnetic field in the spherical cavity, wherein: the spherical cavity is composed of two symmetrical D-shaped electrodes, the straight edges of the two D-shaped electrodes are superposed and vertically overlapped, the two D-shaped electrodes are non-conductive at the joint, and the two D-shaped electrodes are separated by an insulating material; a high-frequency electric field in the spherical cavity, which is generated by the two D-shaped electrodes; a constant magnetic field in the spherical chamber is generated by adding a permanent magnet outside the spherical chamber; the substrate stage is positioned at a position perpendicular to the magnetic field plane and close to the inner wall of the spherical chamber. By utilizing the invention, the automatic phase stabilization principle is applied to the plasma immersion ion implantation technology, thereby realizing the quality separation of immersion ion implantation and solving the problem that single ion single energy implantation can not be realized by immersion ion implantation.

Description

Device for separating ions of different masses in plasma immersion ion implantation

technical field

The invention relates to the technical field of plasma immersion ion implantation, in particular to a device for separating ions of different masses in plasma immersion ion implantation.

Background technique

In the semiconductor manufacturing process, the mainstream impurity doping technology is the traditional beamline ion implantation technology. This method generates plasma (composed of mixed ions, electrons, and neutral particles) from an ion source, and the plasma is analyzed by magnets and other mass-energy The separation system separates the mass and energy of the plasma to obtain ions of single mass and single energy, and then accelerates the separated ions through the acceleration tube, and the accelerated ions are implanted into the substrate (such as a silicon wafer) at high speed. The implantation of the implanted substrate needs to be scanned by means of a scanning system. It can be seen that this method requires complex mass spectrometry and scanning devices, low injection efficiency, complex structure, and high cost.

With the reduction of the feature size of integrated circuits, the reduction of junction depth requires further reduction of ion implantation energy (<1keV), and the reduction of beamline ion implantation beam energy will lead to defects such as beam dispersion, poor uniformity, and further reduction in efficiency. Call for the emergence of new technologies. Plasma immersion ion implantation (PIII) technology can effectively avoid the above problems.

PIII technology is to place the substrate on the electrode of the cathode, and apply a negative bias to the electrode, introduce the required gas into the working chamber of the injection system, and add a power source to the system, and discharge through inductive coupling, capacitive coupling, etc. The method ignites a gas introduced into a chamber to form a plasma. Since there is a negative bias voltage on the cathode, there will be a negative bias sheath near the substrate. Under the acceleration of the high voltage of the sheath, the positive ions in the sheath will pass through the sheath and inject into the substrate. in the film.

As shown in Figure 3, Figure 3 is a schematic diagram of the PIII system without the principle of automatic phase stabilization. At this time, the chamber is cylindrical, and the substrate stage is placed in the center of the chamber to facilitate the uniformity of injection. This method has the following advantages:

1) There is no need to extract ions from the ion source, perform mass spectrometry analysis and linear acceleration on the ions, which greatly simplifies the structure of the implantation equipment and saves a lot of cost;

2) This technology adopts the sheath acceleration mechanism, and the injection process is the whole wafer injection, which has nothing to do with the size of the substrate, so the yield of this technology is extremely high.

It can be seen that PIII technology is a new type of implantation technology that is expected to replace beamline ion implantation. However, in PIII, all ions will be accelerated and implanted into the substrate. How to achieve the separation of implanted ion mass and energy, that is, how to realize the implantation of a single ion with a single energy has always been a major problem in PIII, which seriously affects the development of PIII technology. and promotion.

Contents of the invention

(1) Technical problems to be solved

In view of this, the main purpose of the present invention is to provide a device for separating ions of different masses in plasma immersion ion implantation, so as to apply the principle of automatic phase stabilization to plasma immersion ion implantation technology, and realize the quality of immersion ion implantation. Separation, to solve the problem that immersion ion implantation cannot achieve single ion single energy implantation.

(2) Technical solutions

To achieve the above object, the present invention provides a device for separating ions of different masses in plasma immersion ion implantation, the device comprises a spherical chamber, a substrate stage, a high-frequency electric field in the spherical chamber and a constant magnetic field, where:

The spherical chamber is composed of two symmetrical D-shaped electrodes, the two D-shaped electrodes are overlapped on the straight sides, stacked up and down, and are not conductive at the connection, and separated by insulating materials in the middle;

A high-frequency electric field in the spherical chamber, generated by the two D-shaped electrodes;

The constant magnetic field in the chamber in the spherical chamber is generated by adding a permanent magnet outside the spherical chamber;

The substrate stage is located perpendicular to the magnetic field plane and close to the inner wall of the spherical chamber.

In the above solution, the high-frequency electric field in the spherical chamber is generated by applying a high-frequency voltage to the two D-shaped electrodes.

In the above solution, the constant magnetic field in the spherical chamber is generated by adding left-right symmetrical permanent magnets outside the spherical chamber.

In the above solution, the substrate stage is located at a position perpendicular to the magnetic field plane and close to the inner wall of the chamber.

(3) Beneficial effects

The device for separating different masses of ions in plasma immersion ion implantation provided by the present invention applies the principle of automatic phase stabilization to plasma immersion ion implantation technology, thereby realizing the mass separation of immersion ion implantation and solving the problem that immersion ion implantation cannot be realized The problem of single ion single energy implantation.

Description of drawings

Fig. 1 is a schematic structural diagram of a device for separating ions of different masses in plasma immersion ion implantation provided by the present invention;

Fig. 2 is a structural schematic diagram of a D-shaped electrode;

Fig. 3 is a schematic diagram of a PIII system without an automatic phase stabilization principle in the prior art.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The principle of automatic phase stabilization was first used in accelerators. Phase stabilization accelerators use D-shaped electrodes to accelerate particles, which can simplify a single D-pole structure (as shown in Figure 2). Figure 2 is a schematic diagram of the D-shaped structure and its potential amplitude Distribution, such a potential distribution makes the distribution of the electric field generated in the chamber uniform.

In a steady-phase accelerator, the cyclotron frequency or period of particles varies with time:

为一固定值

且高频频率在开始时与粒子的回旋频率相同，以后随时间的变化率又严格遵循以上关系，那么粒子就能始终保持与高频电场相同的频率旋转，以固定的相位

被同步加。这个粒子被称为理想粒子，称为平衡相位。可见只有注入相位

与平衡相位

相同，并且注入能量ε_i等于粒子静止能量时的粒子才是“理想粒子”。if phase

to a fixed value

And the high-frequency frequency is the same as the whirling frequency of the particle at the beginning, and the rate of change over time strictly follows the above relationship, then the particle can always keep rotating at the same frequency as the high-frequency electric field, with a fixed phase

is added synchronously. This particle is called an ideal particle, called the equilibrium phase. It can be seen that only the injected phase

phase with balance

The same, and the particle when the injected energy ε _i is equal to the rest energy of the particle is the "ideal particle".

However, it is not only "ideal particles" that can be finally accelerated to the final energy. Veksler of the former Soviet Union and Macmillan of the United States independently proposed the principle of automatic phase stabilization in 1944 and 1945: in some resonant accelerators Among them, through the modulation of some accelerator parameters, the motion of the ideal particle accelerated in a certain equilibrium phase can be completely synchronized with the high-frequency electric field, and the energy can increase continuously; while the phase and energy deviate from the ideal particle within a certain range The non-ideal particles will vibrate around the ideal particles, and finally be accelerated to the final energy together with the ideal ions.

For non-ideal particles with ε _i = ε _is , only when in the interval When the particle is inside, the particle can be accelerated to the final energy through stable phase oscillation. Otherwise, the particle cannot be accelerated to the final energy stably.

为稳定的初始相位区的结论。A similar analysis for non-ideal particles with _εi around _εis still yields the same

The conclusion for the stable initial phase region.

与离子质量M有关，即被加速的离子相位区间

对应一个离子质量区间(M，M′)。只有质量在这个区间的离子才能被加速注入到基片中从而从一定程度上实现浸没离子注入的质量分离。Applying the principle of automatic phase stabilization to PIII, the frequency of ions in the plasma is related to the mass of ions: ${\mathrm{\&omega;}}_p={\left(\frac{e^2{\mathrm{no}}_0}{{\mathrm{\&epsiv;}}_{0}m}\right)}^{1/2}$ That is, the frequency of the plasma is inversely proportional to the square root of the ion mass, and the phase It is proportional to the frequency ω _pi . Therefore the phase

It is related to the ion mass M, that is, the accelerated ion phase interval

Corresponds to an ion mass interval (M, M'). Only the ions whose mass is in this range can be accelerated into the substrate so as to realize the mass separation of immersion ion implantation to a certain extent.

As shown in Figure 1, Figure 1 is a schematic structural view of a device for separating ions of different masses in plasma immersion ion implantation provided by the present invention, the device includes a spherical chamber, a substrate stage, a high-frequency electric field in the spherical chamber and A constant magnetic field inside a spherical chamber where:

The spherical chamber is composed of two symmetrical D-shaped electrodes, the two D-shaped electrodes are overlapped on the straight sides, stacked up and down, and are not conductive at the connection, and separated by insulating materials in the middle;

A high-frequency electric field in the spherical chamber, generated by the two D-shaped electrodes;

The constant magnetic field in the chamber in the spherical chamber is generated by adding a permanent magnet outside the spherical chamber;

The substrate stage is located perpendicular to the magnetic field plane and close to the inner wall of the spherical chamber.

Wherein, the high-frequency electric field in the spherical chamber is generated by applying high-frequency voltage to the two D-shaped electrodes. The constant magnetic field in the spherical chamber is generated by adding left-right symmetrical permanent magnets outside the spherical chamber. The substrate stage is located perpendicular to the magnetic field plane and close to the inner wall of the chamber, and the substrate stage is placed on the leftmost or rightmost side of the chamber to facilitate better screening of ions.

The invention proposes to apply the principle of automatic phase stabilization to the plasma immersion ion implantation technology, so as to realize the mass separation of the immersion ion implantation, and solve the problem that the immersion ion implantation cannot realize single ion single energy implantation. Applying the principle of automatic orientation stabilization to immersion ion implantation needs to apply a high-frequency electric field longitudinally in the chamber and a constant magnetic field laterally in the chamber. The vertical high-frequency electric field is obtained by applying high-frequency voltage to the D row electrode structure. A constant magnetic field is obtained by adding a permanent magnet.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. A device for separating different mass ions in plasma immersion ion implantation, characterized in that the device comprises a spherical chamber, a substrate stage, a high-frequency electric field in the spherical chamber and a constant magnetic field in the spherical chamber, wherein : The spherical chamber is composed of two symmetrical D-shaped electrodes, the two D-shaped electrodes are overlapped on the straight sides, stacked up and down, and are not conductive at the connection, and separated by insulating materials in the middle; A high-frequency electric field in the spherical chamber, generated by the two D-shaped electrodes; The constant magnetic field in the chamber in the spherical chamber is generated by adding a permanent magnet outside the spherical chamber; The substrate stage is located perpendicular to the magnetic field plane and close to the inner wall of the spherical chamber. 2. The device for separating different mass ions in plasma immersion ion implantation as claimed in claim 1, wherein the high-frequency electric field in the spherical chamber is obtained by adding a high-frequency electric field on the two D-shaped electrodes. voltage is generated. 3. The device for separating different mass ions in plasma immersion ion implantation as claimed in claim 1, wherein the constant magnetic field in the spherical chamber is obtained by adding left-right symmetrical permanent magnets outside the spherical chamber. produce.

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