Photoelectric-assisted PECVD (plasma enhanced chemical vapor deposition) equipment

Abstract

The utility model relates to photoelectric auxiliary PECVD (Plasma Enhanced Chemical Vapor Deposition) equipment which is characterized by comprising a frame body, a cavity is arranged in the frame body, the cavity is provided with a heating base serving as a lower electrode, the heating base is used for bearing a substrate, an upper cover plate serving as an upper electrode is arranged above the heating base, and a lower cover plate serving as a lower electrode is arranged above the upper cover plate. The upper cover plate is used for shunting a driving gas introduced into the cavity, the upper cover plate and the heating base can mutually correspond to form a frequency electric field so as to ionize the driving gas, an alternating magnetic field is arranged near the heating base, and the alternating magnetic field is used for driving charged particles to transversely move so as to enlarge the movement track of the charged particles. And the probability of collision ionization between charged particles and gas molecules is increased. The utility model has the following advantages and effects: the cost can be ensured, and the overall ionization rate can be improved at the same time.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of plasma chemical vapor deposition, specifically relates to a photoelectricity assisted PECVD deposition equipment. BACKGROUND

[0002] Plasma Enhanced Chemical Vapor Deposition (PECVD) is a technology that uses plasma energy to promote chemical reactions at lower temperatures, resulting in the deposition of solid thin films on a substrate surface.

[0003] In the reaction process of PECVD, the ionization rate directly affects the characteristics of the plasma, and then affects the deposition quality and rate of the thin film. Higher ionization rate means more gas molecules are ionized into ions and electrons, which increases the activity of the plasma, thereby improving the deposition rate and the quality of the thin film. However, too high ionization rate can cause too high ion energy, increasing damage to the substrate.

[0004] To solve this problem, in the existing design, for example, VHF-PECVD (Very High Frequency Plasma Enhanced Chemical Vapor Deposition) system, VHF-PECVD technology is adopted. Because the plasma excited by VHF has lower electron temperature and higher density than the plasma generated by conventional radio frequency, it can greatly improve the deposition rate of the thin film; or MWECR-PECVD (Microwave Electron Cyclotron Resonance Plasma Enhanced Chemical Vapor Deposition) uses the cyclotron resonance effect of electrons in the microwave and magnetic field to form a high-activity and high-density plasma under vacuum conditions for gas phase chemical reaction.

[0005] However, VHF-PECVD equipment usually needs to use high-frequency power supply and special electrode design, which increases the manufacturing cost and maintenance difficulty of the equipment; and in the MWECR-CVD technology, multiple electromagnetic coils are generally used to combine to generate and adjust the axial magnetic field required for electron cyclotron resonance and thin film deposition. Because the coil volume is large, and each coil needs to be configured with a power supply separately, the device structure is large, energy-consuming, and expensive.

[0006] Therefore, as described above, when using VHF-PECVD and MWECR-PECVD technology to improve ionization rate, it is accompanied by high cost. SUMMARY

[0007] In view of the deficiencies in the prior art, the purpose of the utility model is to provide a photoelectricity assisted PECVD deposition equipment which can ensure the cost while improving the overall ionization rate.

[0008] To achieve the above object, the utility model provides a kind of photoelectricity assisted PECVD deposition equipment, including frame, chamber is equipped in the frame, the chamber is equipped with heating base as lower electrode, the heating base is used to carry substrate, the upper side of the heating base is equipped with upper cover plate as upper electrode, the upper cover plate is used to shunt the drive body gas that is passed into chamber, the upper cover plate can be mutually echoed with heating base and form frequency radiation electric field, to ionize drive body gas, alternating magnetic field is equipped near the heating base, the alternating magnetic field is used to drive charged particle lateral movement, to expand the trajectory of charged particle movement, increase the probability of collision ionization of charged particle and gas molecule.

[0009] The utility model further provides: the upper cover plate is located and is equipped with upper layer gas net and lower layer gas net in succession along vertical direction from top to bottom on the side towards heating base, the upper cover plate is shunted to the drive body gas that is passed into chamber by upper layer gas net and lower layer gas net.

[0010] The utility model further provides: the upper layer gas net is equipped with the upper layer shunt hole of penetration, the upper layer shunt hole is multiple and interval arrangement, the upper layer shunt hole inner diameter is successively reduced from top to bottom and forms inverted trapezoidal structure, the lower layer gas net is equipped with the lower layer shunt hole of penetration, the lower layer shunt hole is multiple and interval arrangement, the lower layer shunt hole inner diameter is successively reduced from top to bottom and forms inverted trapezoidal structure, the lower layer shunt hole specification is less than upper layer shunt hole.

[0011] The utility model further provides: square electromagnetic induction coil is equipped in the heating base, square electromagnetic induction coil is connected with external alternating power source, to form alternating magnetic field.

[0012] The utility model further provides: the upper side of the heating base is equipped with ultraviolet light beam emitter, ultraviolet light beam emitter is set up in heating base both sides, and is fixed in frame inside, ultraviolet light beam emitter is used to produce ultraviolet light, to the secondary excitation of drive body gas by frequency radiation electric field ionization.

[0013] The utility model further provides: the lower side of ultraviolet light beam emitter is equipped with electromagnet, electromagnet is located in heating base both sides, and is fixed in frame inside, electromagnet energization is used to produce deceleration magnetic field parallel to heating base, the deceleration magnetic field is used to slow down the running speed of charged particle vertical direction.

[0014] The utility model further provides: the top and bottom both sides of frame are equipped with gas inlet line and exhaust pipe line respectively, gas inlet line and exhaust pipe line are all communicated with chamber, gas inlet line is opposite to upper cover plate.

[0015] The utility model further sets up: the heating base is equipped with double -deck heating coil, double -deck heating coil is used for heating to wafer, double -deck heating coil is located above square electromagnetic induction coil.

[0016] The utility model further sets up: the heating base is equipped with temperature detection device, temperature detection device is used for detecting wafer temperature, temperature detection device includes thermocouple and the instrument cluster of thermocouple electric connection, one end of thermocouple extends to heating base outside as contact end, and the contact end is contacted with wafer.

[0017] Compared with the prior art, the utility model has the beneficial effects that:

[0018] Because the alternating magnetic field is arranged near the heating base, the charged particles (such as electrons, ions) generated by ionization can be driven to move spirally along the transverse direction (parallel to the surface of the wafer) after the charged ions pass through, expanding the motion trajectory and increasing the collision probability with gas molecules, thereby improving the ionization rate. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is the whole structure schematic diagram of the utility model;

[0020] Figure 2 It is the structure schematic diagram of the upper layer gas net and the lower layer gas net in the utility model;

[0021] Figure 3 It is the structure schematic diagram of square electromagnetic induction coil in the utility model;

[0022] Figure 4 It is the structure schematic diagram of ultraviolet light beam emitter in the utility model;

[0023] Figure 5 It is the principle schematic diagram of ultraviolet light beam emitter in the utility model;

[0024] Figure 6 It is the structure schematic diagram of electromagnet in the utility model;

[0025] Figure 7 It is the structure schematic diagram of double -deck heating coil in the utility model. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0027] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] As Figure 1 shown, the utility model discloses a photoelectricity auxiliary's PECVD deposition equipment, including frame 1, and frame 1 is equipped with the sealed chamber 101. In the PECVD technical field, the drive body gas that is ionized is formed between the upper electrode and the lower electrode connected with the radio frequency power supply, in this scheme, the chamber 101 bottom is equipped with the heating base 2 as the lower electrode, for carrying the wafer, and the heating base 2 top is equipped with the upper cover plate 3 as the upper electrode, both are connected with the external radio frequency power supply, to form the radio frequency electric field. The chamber 101 top and bottom are equipped with the gas inlet pipeline 7 and the exhaust pipeline 8 respectively, are used for driving the body gas (such as SiH4, NH3) and discharging by-product respectively;

[0029] In addition, in the PECVD technical field, the lifting pin 100 will be equipped in the heating base 2, when the wafer is advanced to the chamber 101 by the external mechanical hand, the lifting pin 100 gives the wafer support point by rising, and then slowly descends, to ensure that the wafer is stably placed in the wafer area on the heating base 2, the lifting pin 100 can adopt the existing structure, so it is not described in detail.

[0030] As Figure 1 and Figure 2 shown, after the drive body gas is introduced into the chamber 101 through the gas inlet pipeline 7 located at the top of the chamber 101 and opposite to the upper cover plate 3, the introduced drive body gas can be shunted through the upper cover plate 3. Specifically, the side of the upper cover plate 3 facing the heating base 2 is provided with an upper gas net 31 and a lower gas net 32 to sufficiently shunt the originally relatively concentrated drive body gas and form the primary distribution of the drive body gas. Both gas nets are made of high-temperature-resistant insulating material (such as ceramic), and the surface is distributed with multiple groups of inverted trapezoidal shunt holes:

[0031] Upper layer gas network 31: provided with a plurality of upper layer shunt holes 311 distributed at intervals, the hole diameter gradually decreases from top to bottom, forming an inverted trapezoidal structure;

[0032] Lower layer gas network 32: provided with a plurality of lower layer shunt holes 321, which are also inverted trapezoidal in shape, but have smaller hole diameters and higher distribution density than the upper layer. Thus, the design can further refine the primary distributed carrier gas to a great extent. At the same time, the trapezoidal structure of the lower layer shunt hole 321 can give the gas flow (the flow direction of the carrier gas) a certain angle, to a certain extent, control the gas flow, avoid excessive divergence of the gas flow, and at the same time, effectively guide the direction of the carrier gas, and also control the initial motion trajectory of the charged particles (such as electrons and ions) generated by the ionization of the subsequent carrier gas.

[0033] In addition, the above-mentioned gas network design realizes uniform distribution of carrier gas by gradually compressing the carrier gas flow channel, avoiding local concentration that leads to uneven deposition.

[0034] As shown in Figure 1 and Figure 3 , a square electromagnetic induction coil 4 is embedded in the heating base 2, which is made of copper winding and connected with the external alternating power supply. After power-on, an alternating electric field is formed, and at the same time, an alternating magnetic field in the vertical direction is generated. Charged particles are affected by the Lorentz force generated by the alternating magnetic field, and their motion radius expands or shrinks according to the frequency of the alternating electric field. Thus, the charged particles generated by ionization can be driven to move spirally along the horizontal direction (parallel to the surface of the substrate), expand their motion trajectory, increase the collision probability with gas molecules, and thus improve the ionization rate.

[0035] In addition, due to the existence of alternating magnetic field, the change of magnetic flux easily produces large-scale eddy current. In order to reduce the influence of eddy current, the square electromagnetic induction coil 4 should further improve the coil resistance while ensuring high magnetic permeability, reduce the coil eddy current heating, use a low-turn coil to limit the effective magnetic path length, and control the current size in the square electromagnetic induction coil 4 by controlling the output power of the alternating power supply, so as to better stabilize the magnetic field strength and reduce the influence of eddy current as much as possible.

[0036] As shown in Figure 1 and Figure 4 and Figure 5 , an ultraviolet beam emitter 5 is installed on the inner wall of the frame 1 on both sides of the heating base 2. The ultraviolet beam emitter 5 is used to produce ultraviolet light to perform secondary excitation on the carrier gas ionized by the radio frequency electric field. The ultraviolet beam emitter 5 adopts the existing structure, which mainly consists of a semiconductor laser (LD) 51, a focusing lens 52, a Nd:YAG laser crystal 53, and a frequency doubling crystal 54. This is a conventional structure, so it will not be described in detail here.

[0037] In addition, it should be noted that in the ultraviolet light beam emitter 5, a small hole structure is adopted, so that the device emits a "light beam" rather than pure light. The reason for this is that the substrate absorbs ultraviolet light, and the absorption capacity of the substrate increases significantly in the 150-400 nm ultraviolet light region, especially in the 195 nm ultraviolet light region, which reaches the maximum absorption rate. Therefore, in order to prevent the dispersion of ultraviolet light from affecting the bottom substrate, it is necessary to significantly limit the range of action of ultraviolet light in this way, and to reduce the influence of scattered light on the magnetic field and the magnetic light effect caused by deflection.

[0038] At the same time, since SiH4 is the most commonly used driving gas in PECVD technology, in order to ensure the photochemical reaction of SiH4 in the ultraviolet light beam region, the wavelength of the ultraviolet light is preferably set to between 200 nm and 280 nm, i.e. the ultraviolet light in the UVC band. In the case of as low as possible absorption of ultraviolet light by the substrate, the effect of ultraviolet light on the SiH4 chemical reaction is ensured.

[0039] In addition, after the ultraviolet light irradiates the electrons, it will excite the electrons and make them gain energy, resulting in a transition. The light beam-shaped ultraviolet light is beneficial to control the movement direction of the excited electrons, avoid a large deviation of the movement direction of the electrons, and to a certain extent, limit the region of electron excitation, avoid too many electrons excited to gain energy and cause uncontrolled ionization region.

[0040] As shown in Figure 1 and Figure 6 , the electromagnet 6 is fixed on the inner wall of the frame 1 on both sides of the heating base 2, and the arrow direction in the figure is the current direction. The electromagnet 6 is located below the ultraviolet light beam emitter 5 and generates a deceleration magnetic field (static magnetic field) parallel to the surface of the substrate after being energized, and by adjusting the current size, the strength of the deceleration magnetic field can be adjusted. The deceleration magnetic field is perpendicular to the longitudinal (vertical to the substrate) movement direction of the charged particles, and slows down the particles through the Lorentz force to bombard the substrate, so as to slow down and reduce the risk of substrate damage, and prolong the residence time of the charged particles in the chamber 101, promoting uniform deposition.

[0041] As shown in Figure 1 and Figure 7As shown, the heating base 2 is provided with a double-layer heating coil 9 for heating the substrate, and the double-layer heating coil 9 is located above the square electromagnetic induction coil 4. In the design of the double-layer annular heating coil, from the outer ring to the inner ring, a design of uniformly arranging large rings around small rings is adopted to ensure that the surface temperature of each region can uniformly rise when the substrate is heated and warmed on the heating base 2, and to avoid temperature imbalance during heating and warming. The power supply module for supplying power to the heating coil includes a power supply and a temperature detection device for temperature monitoring of the heating of the heating base 2 to avoid heat accumulation caused by excessive temperature and thus affect the material quality of the heating base 2.

[0042] At the same time, in order to avoid affecting the substrate and the heating base 2, low magnetic permeability and high resistivity materials should be used for the coil material to reduce the change of magnetic flux and weaken the influence of eddy current as much as possible. The low magnetic permeability material will also greatly weaken the magnetic field generated by the electric field and reduce the interference with other preset magnetic fields as much as possible.

[0043] In addition, the temperature detection device can monitor the temperature of the substrate in real time. Since the temperature detection device is embedded in the heating base 2, the temperature detection device also needs to be thermally insulated, that is, at least several centimeters thick asbestos is used to thermally insulate the temperature detection device around the temperature detection device, which can insulate the temperature conduction of the heating base 2 and avoid the influence of the peripheral temperature on the temperature detection device.

[0044] The above-mentioned temperature detection device mainly includes a thermocouple 91 and a meter panel electrically connected with the thermocouple 91. Specifically, the reference end (cold end) of the thermocouple 91 is connected with the reference end of the meter panel, the measurement end (hot end) of the thermocouple 91 is connected with the measurement end of the meter panel, and the power supply end of the meter panel is connected with the corresponding external power supply. In this way, by extending the contact end of the thermocouple 91 to the surface of the heating base 2 and directly contacting the substrate, the temperature of the substrate can be monitored in real time.

[0045] The implementation process of the device is as follows:

[0046] The substrate is first transferred by an external robot, the lifting pin 100 is lifted to provide a support point for the substrate, and then slowly lowered to ensure that the substrate is stably placed on the slide area of the heating base 2, the vacuum pump is started to draw the chamber 101 to the target pressure, at this time, the corresponding power supply is powered on to the double-layer annular heating coil, the temperature of the substrate is monitored by the temperature detection device, the substrate is heated to the predetermined temperature, the gas inlet pipeline 7 starts to introduce the carrier gas, the gas is divided by the upper gas net 31 and the lower gas net 32 of the upper cover plate 3, so that the originally concentrated gas flow is dispersed and the distribution is more uniform, at the same time, the upper cover plate 3 serves as the upper electrode, under the action of the alternating power supply, it forms a response with the heating base 2 as the lower electrode to form a radio frequency electric field in the middle part of the chamber 101, due to the existence of the radio frequency electric field, the uniform gas flow that is divided will be ionized at the beginning, and part of the charged particles will move with the carrier gas flow;

[0047] The area between the upper cover plate 3 and the ultraviolet beam generator can be regarded as a primary ionization area, and the ionization is mainly caused by the radio frequency electric field generated by the upper and lower electrodes. Then, the charged particles of the reaction process enter the ultraviolet light coverage area generated by the ultraviolet beam generator 5 driven by the gas flow, and part of the carrier gas, such as SiH4(silane), will undergo photochemical reaction under the irradiation of ultraviolet light to generate free-state charged particles. At this time, the charged particles from the primary ionization area and the newly generated charged particles form secondary excitation under the irradiation of ultraviolet light, collide with the carrier gas molecules to form collision ionization. In this process, the secondary excited electrons will be affected by the alternating magnetic field generated by the square electromagnetic induction coil 4 in the base, which will expand their own motion trajectory in the horizontal direction, so as to further improve the ionization degree of the carrier gas and continue to move downward along the gas flow;

[0048] When the gas flow reaches the area covered by the electromagnet 6, the magnetic field generated by the electromagnet 6 parallel to the heating base 2 will make the charged particles in the gas flow subjected to the vertical upward Lorentz force, and slow down the corresponding vertical velocity component, until the reaction on the substrate surface. During the reaction on the substrate surface, the by-products generated by the reaction will be carried by the gas flow to the exhaust pipeline 8 at the bottom of both sides to be discharged, so as to avoid the accumulation of by-products in the chamber 101 to cause pollution.

[0049] The specific embodiment is only an explanation of the utility model, and is not a limitation of the utility model. Those skilled in the art can make modifications to the embodiment without creative contribution after reading the specification, but as long as it is within the scope of the claims of the utility model, it is protected by the patent law.

Claims

1. A photo-electricity assisted PECVD deposition apparatus, characterized in that, The application relates to a frame body, wherein a cavity is arranged in the frame body, the cavity is provided with a heating base serving as a lower electrode and used for carrying a substrate, an upper cover plate serving as an upper electrode is arranged above the heating base and is used for distributing a carrier gas into the cavity, the upper cover plate can be in resonance with the heating base to form a radio frequency electric field for ionizing the carrier gas, an alternating magnetic field is arranged near the heating base and is used for driving charged particles to move transversely to expand the moving track of the charged particles and increase the probability of collision ionization between the charged particles and gas molecules.

2. A photo-assisted PECVD deposition apparatus according to claim 1, wherein, The upper cover plate is provided with an upper gas net and a lower gas net arranged in sequence from top to bottom in a vertical direction on the side facing the heating base, and the upper cover plate distributes the carrier gas into the cavity through the upper gas net and the lower gas net.

3. A photo-assisted PECVD deposition apparatus according to claim 2, wherein, The upper gas net is provided with upper distribution holes penetrating through the upper gas net, the upper distribution holes are multiple and are arranged at intervals, the inner diameters of the upper distribution holes are sequentially reduced from top to bottom to form an inverted trapezoidal structure, the lower gas net is provided with lower distribution holes penetrating through the lower gas net, the lower distribution holes are multiple and are arranged at intervals, the inner diameters of the lower distribution holes are sequentially reduced from top to bottom to form an inverted trapezoidal structure, and the specification of the lower distribution holes is smaller than that of the upper distribution holes.

4. The opto-electric assisted PECVD deposition apparatus of claim 1, wherein, The heating base is provided with a square electromagnetic induction coil connected with an external alternating power supply to form an alternating magnetic field.

5. The opto-electric assisted PECVD deposition apparatus of claim 1, wherein, The upper side of the heating base is provided with ultraviolet beam emitters arranged on both sides of the heating base and fixed to the inner side of the frame body, and the ultraviolet beam emitters are used for generating ultraviolet light to secondarily excite the carrier gas ionized by the radio frequency electric field.

6. An opto-electrically assisted PECVD deposition apparatus according to claim 5, wherein, The lower side of the ultraviolet beam emitters is provided with electromagnets arranged on both sides of the heating base and fixed to the inner side of the frame body, the electromagnets are electrified to generate a deceleration magnetic field parallel to the heating base, and the deceleration magnetic field is used for slowing down the vertical running speed of the charged particles.

7. The opto-electric assisted PECVD deposition apparatus of claim 1, wherein, The top end and the bottom end of the frame body are respectively provided with an air inlet pipeline and an air outlet pipeline, the air inlet pipeline and the air outlet pipeline are communicated with the cavity, and the air inlet pipeline is opposite to the upper cover plate.

8. A photo-assisted PECVD deposition apparatus as claimed in claim 4, characterized in that, The heating base is provided with a double-layer heating coil used for heating the substrate, and the double-layer heating coil is arranged above the square electromagnetic induction coil.

9. An opto-electrically assisted PECVD deposition apparatus according to claim 8, characterized in that, The heating base is provided with a temperature detection device used for detecting the temperature of the substrate, the temperature detection device comprises a thermocouple and an instrument panel electrically connected with the thermocouple, one end of the thermocouple extends to the outside of the heating base as a contact end, and the contact end is in contact with the substrate.

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