TWI639178B - Plasma assisted atomic layer deposition apparatus - Google Patents

Abstract

The invention provides a plasma assisted atomic layer coating device, which mainly comprises a reaction cavity, a plurality of feed lines, a vacuum pump and an RF module. The reaction cavity comprises an electrode plate and a heating plate; the RF module mainly comprises an RF power source, an impedance matching device and a plurality of impedance matching transmission lines. By adjusting the number and position of the electrode plates connected to the impedance matching transmission line in the reaction chamber, the RF module can quickly provide low reflection UHF power to the electrode plate and can be used in a large area electrode plate. A stable and uniform electromagnetic wave distribution is obtained.

Description

Plasma assisted atomic layer coating device

The present invention relates generally to an atomic layer coating apparatus, and more particularly to an ultra-high frequency plasma assisted atomic layer coating apparatus having impedance matching.

Atomic layer deposition technology uses the process gas to chemically adsorb the surface of the material. Since the reaction only reacts on the surface, it has self-limited characteristics, so that each time the growth cycle, only a layer of atomic film is formed on the surface. It can control the film thickness up to the atomic level (0.1 nm), which is the coating technology for the highest quality film in all existing coating methods.

Atomic layer deposition technology can be used for ultra-thin high-k material coating, and can also provide hole filling capability for small circuit structures in dynamic random access memory (Dynamic Random Access Memory) with high aspect ratio. DRAM) provides a uniform thickness coating in the capacitor structure and MEMS components; on the component package, the atomic layer deposition technique with high density is gradually introduced into the package of the Organic Light-Emitting Diode (OLED) component.

The biggest disadvantage of atomic layer deposition technology is the slow deposition rate. Batch equipment and plasma-assisted atomic layer deposition can improve the productivity of atomic layer deposition process. Plasma-assisted atomic layer deposition equipment utilizes atomic radicals generated by plasma and other atoms and molecules in the excitatory state (such as hydrogen atoms, oxygen atoms, nitrogen atoms) to strengthen the traditional atomic layer deposition process, which can be used at low temperatures. Depositing, and multiple choice of precursors, but its plasma damage is a problem to be solved.

In the plasma enhanced chemical vapor deposition process, the plasma is excited by RF power, and the increase in RF frequency in the plasma can increase the coating rate and reduce the plasma damage caused by bombardment. When the area of the substrate to be coated is increased, the radio frequency electromagnetic wave transmitted thereon will cause the electric field to change due to the phase change, and relatively affect the uniformity of the plasma and the quality of the subsequent coating. Especially in today's display factories and solar plants, the cavity area used is more than one square meter, and the instability of radio frequency electromagnetic waves in the cavity will seriously affect the mass production of components.

Reference is made to U.S. Patent No. 6,228,438, entitled,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, The surface of the electrode plate is distributed by a Gaussian elliptic function to match the electric field distribution to produce a uniform plasma. However, the device disclosed in this case cannot be used in an upright electrode cavity to reduce the area occupied by the device. In view of the thin film solar cell coating process, it is often necessary to use a vertical cavity to increase the number of single-production substrates and reduce the process cost. Therefore, an upright structural device is required to achieve the goal of reducing cost and depositing a uniform thickness film.

Further, reference is made to U.S. Patent No. 7,141,516, entitled,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, The ladder electrode adopts a linear phase matching of the tubular electrodes in a one-to-many manner to achieve an electric field uniformly distributed over a large area, thereby generating a uniformly distributed plasma. However, the electrode plate requires a phase shifter and a plurality of sets of impedance adjusters to achieve the effect.

In order to solve the above problems, there is a need to provide a plasma-assisted atomic layer coating apparatus capable of producing a uniform plasma at an ultra-high frequency to overcome the disadvantages of the prior art.

The main object of the present invention is to provide an ultra-high frequency plasma-assisted atomic layer coating device which can quickly provide ultra-high frequency power to an electrode plate in a reaction chamber, reduce power reflection, and can be uniformly obtained on a large-area electrode plate. The electromagnetic wave distribution.

In order to achieve the object of the present invention, the present invention provides a plasma assisted atomic layer coating apparatus for a chemical vapor deposition system, comprising: a reaction chamber having a plurality of gas inlet holes and a plurality of gas outlet holes, An electrode plate and a heating plate are disposed in the reaction chamber, and the outer surface of the reaction chamber is grounded; a plurality of feed lines are connected to the plurality of air inlet holes; and the vacuum pump has a plurality of air suction lines. Connected to a plurality of air outlets; an RF module disposed outside the reaction chamber for providing an ultra-high frequency power to the reaction chamber. The RF module includes an RF power source for providing the UHF power; an impedance matching device electrically connected to the RF power source for adjusting the plasma impedance of the reaction chamber; and a plurality of impedance matching The transmission line is electrically connected between the impedance matching device and the electrode plate. The impedance of one of the impedance matching transmission lines is between 1 and 50 ohms, and the number of the impedance matching transmission lines is a power of 2, and the symmetric distribution is connected to the area of the electrode plate to evenly distribute the ultra high frequency. Power is applied to the electrode plate.

According to a feature of the invention, the impedance matching transmission line and the impedance matching unit further comprise a power distribution transmission line, and the impedance matching transmission line impedance is smaller than the impedance of the power distribution transmission line.

According to one feature of the present invention, the ultra high frequency power provided by the radio frequency module The frequency is between 20 and 90 MHz.

According to a feature of the present invention, the impedance matching transmission lines are overwritten Layer ceramic insulation.

The plasma assisted atomic layer coating device of the invention has the following effects:

1. For different frequency RF power, the number of transmission lines can be changed accordingly, thereby achieving the effect of reducing power reflection, providing stable power to the reaction cavity, thereby increasing the deposition thickness of each deposition cycle.

2. The electric field strength of the electrode plate is changed by the input path of the plurality of impedance matching transmission lines, thereby changing the distribution of the plasma, achieving a uniform plasma distribution pattern of a large area, and improving the uniformity of the deposited film.

In order to make the objects, features and advantages of the present invention more comprehensible, the following detailed description of the preferred embodiments and the accompanying drawings.

100‧‧‧ Plasma Auxiliary Atomic Layer Coating Device

110‧‧‧Reaction chamber

111‧‧‧ Grounding

112‧‧‧electrode plate

114‧‧‧heating plate

121,122‧‧‧feed line

123,124‧‧‧Air intake

125‧‧‧Exhaust line

126‧‧‧ Vents

131‧‧‧vacuum pump

141‧‧‧RF Module

143‧‧‧RF power source

144‧‧‧impedance matcher

145‧‧‧ Grounding

146‧‧‧ impedance matching transmission line

The above and other objects, features, and advantages of the present invention will become more apparent and understood. While the invention may be embodied in various forms, the embodiments illustrated in the drawings It is not intended to limit the invention to the particular embodiments illustrated and/or described.

Figure 1 is a schematic view of a plasma assisted atomic layer coating apparatus of the present invention.

Figure 2a is a top plan view of an embodiment of an impedance matching transmission line to an electrode plate.

Figure 2b is a top plan view of another embodiment of an impedance matching transmission line to an electrode plate.

Figure 2c is a top plan view of another embodiment of an impedance matching transmission line to an electrode plate.

The invention will be more fully understood from the following detailed description of the drawings. Certain illustrative embodiments are now described to provide a comprehensive understanding of the structure, function, One or more embodiments of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will recognize that the devices and methods that are specifically described herein and illustrated in the drawings are non-limiting exemplary embodiments, and the scope of the invention is defined only by the scope of the claims. Features illustrated or described in connection with an exemplary embodiment may be combined with features of other embodiments. Such modifications and variations are intended to be included within the scope of the invention.

The present invention may be embodied in a different form of embodiment, and the following description of the invention is intended to be a preferred embodiment of the invention. It is not intended to limit the invention to the particular embodiments illustrated and/or described.

The typical atomic layer coating film formation mechanism is roughly divided into four steps:

Step 1: In a first time zone, the precursor A is injected and adsorbed on the surface of the substrate, and the injected precursor reacts with the surface of the substrate. This reaction is self-limiting and the excess precursor is no longer adsorbed onto the adsorbed precursor molecules.

Step 2: In the second time zone, remove excess unreacted precursors and by-products after the reaction. In this step, unreacted precursors and by-products are carried away from the reaction chamber by injecting an inert gas such as nitrogen or argon, and pumping the vacuum pump.

Step 3: In a third time zone, the precursor B is injected and adsorbed on the surface of the substrate to form a newly bonded compound.

Step 4: In the fourth time zone, the excess unreacted precursor B and the by-products after the reaction are removed. This step is also performed by injecting an inert gas such as nitrogen or argon, and the true The empty pump draws air, and the unreacted precursor B and by-products are carried away from the reaction chamber.

Usually, the four steps are completed in one cycle, and each cycle completes film formation with a thickness close to one atomic level. To increase the thickness of the film, it is necessary to continue the cycle of the above four steps.

Due to the chemical nature of atomic layer coating growth, not all materials are suitable for growth with atomic layer coating. Therefore, by means of the plasma-assisted method, it is possible to grow a thin film material which cannot be grown by a conventional heated atomic layer coating.

The plasma assisted atomic layer coating device 100 disclosed in the present invention is similar to the conventional atomic layer coating method in that the first precursor A is adsorbed on the surface of the substrate in a self-limiting manner. However, in the plasma assisted atomic layer coating apparatus process, after the second precursor B is injected into the reaction chamber, plasma treatment is applied, that is, the second precursor B is excited into a plasma state.

Since the plasma excites to form many free radicals, its free radicals can help bond the film and form a reaction surface that is favorable for the next reaction, so it can grow at a lower process temperature. Therefore, the reaction is not limited by insufficient heat. Therefore, the plasma can provide free radicals to increase its reactivity, making the reaction more complete at low temperatures.

The plasma-assisted atomic layer coating apparatus 100 disclosed in the present invention is suitable for growing a metal thin film, and can be accelerated by a plasma-assisted method so as not to be limited by the initial film nucleation and the growth rate is reduced.

Referring to FIG. 1 , a plasma assisted atomic layer coating apparatus 100 according to the present invention includes: a reaction chamber 110; a plurality of feed lines 122, 124; a vacuum pump 130; and a radio frequency module 140. .

The reaction chamber 110 has a plurality of air inlets 123, 125 and an air outlet 126. The reaction chamber is provided with an electrode plate 112 and a heating plate 114, and the outer surface of the cavity is grounded 111. The feed lines are connected to the reaction chamber 110 The intake holes, for example, the feed line 122 are connected to the intake hole 123 of the reaction chamber 110, and the feed line 124 is connected to the intake hole 125 of the reaction chamber 110.

The vacuum pump 130 is connected to the air outlet 127 of the reaction chamber 110 by an air suction line 126. The vacuum pump 130 can be realized by a conventional vacuum pump. The vacuum pump 130 is used to draw the pressure inside the reaction chamber 110 between 0.5 and 760 Torr during the process.

The RF module 140 is disposed outside the reaction chamber 110 for providing an ultra-high frequency power to the reaction chamber 110. The RF module 140 includes a RF power source 142; an impedance matcher 144; and a plurality of impedance matching transmission lines 146.

The RF power source 142 is used to provide the UHF power and the other end is electrically grounded 145. The impedance matcher 144 is electrically connected to the RF power source 142 for adjusting the plasma impedance of the reaction chamber 110. The frequency of the ultra high frequency power provided by the RF power source 142 of the RF module 140 is between 20 and 90 MHz. Preferably, in an embodiment, the frequency of the UHF power provided by the RF power source 142 of the RF module 140 is 40.68 MHz.

The impedance matching transmission lines 146 are electrically connected between the impedance matching unit 144 and the electrode plate 112. The UHF power from the RF power source 142 is distributed to the electrode plate 112 by the power distribution between the impedance matching transmission line 146 and the impedance matcher 144.

The impedance of one of the impedance matching transmission lines 146 is between 1 and 50 ohms. Preferably, the impedance of the impedance matching transmission line 146 is between 30 and 50 ohms. The impedance matching transmission line 146 has a larger impedance than the reaction cavity 110. Plasma impedance. Preferably, the impedance matching transmission lines 146 are coaxial cables having an impedance of 50 ohms.

Referring to FIG. 2, a top view of the relationship between the impedance matching transmission line and the electrode plate disclosed in the present invention is shown, wherein the frequency of the RF power is 40.68 MHz. The number of the impedance matching transmission lines 146 is a power of two, and the symmetric distribution is connected to the area of the electrode plate 112 to evenly distribute the ultra high frequency power to the electrode plate 112. That is, the number of the impedance matching transmission lines 146 is 2, 4, 8, 16, 32, 64, 128, and the like. The number of impedance matching transmission lines 146 is selected from one of 2, 4, and 8. Preferably, the number of the impedance matching transmission lines 146 is four.

The impedance seen by the RF power source 142 to the impedance matching transmission lines 146 is referred to as a feed impedance. By the impedance matching transmission line 146 relative to the connection position with the electrode plate 112, the feed impedance can be effectively adjusted at an appropriate impedance, and the plasma impedance of the RF power source 142 and the reaction chamber can be reduced. The difference is thereby such that the power of the RF power source 142 achieves maximum transmission efficiency.

Referring now to Figure 2a, there is shown a top view of an embodiment of the relationship between the impedance matching transmission line and the electrode plate of the present invention, in a preferred embodiment of the present invention. Two sets of the impedance matching transmission lines 146 are connected to the center of the electrode plate 112.

Referring now to FIG. 2b, there is shown a top view of another embodiment of the relationship between the impedance matching transmission line and the electrode plate of the present invention, using two sets of impedance matching transmission lines 146, but different from the second embodiment, The two sets of impedance matching transmission lines 146 and the electrode plate 112 are in a diagonal form.

Referring now to FIG. 2c, there is shown a top view of another embodiment of the relationship between the impedance matching transmission line and the electrode plate of the present invention. The four sets of impedance matching transmission lines 146 can correspond to the higher frequency RF power. The shorter wavelength.

The materials of the impedance matching transmission lines 146 are selected from the group consisting of nickel, gold, silver, titanium, copper, palladium, stainless steel, beryllium copper alloy, aluminum, coated aluminum, and combinations thereof. The impedance matching transmission lines 146 are further coated with a layer of ceramic insulating material. The material of the layer of ceramic insulating material is selected from the group consisting of cerium oxide, aluminum oxide, zirconium oxide, titanium oxide, and combinations thereof.

The electrode plate 112 has a plurality of venting perforations and connects at least one of the plurality of intake holes. Alternatively, the lower edge of the electrode plate 112 may increase the arrangement of a diffusion plate 113, thereby increasing the dispersion of the second precursor B into the reaction chamber 110. The venting perforations provided in the electrode plate 112 can reduce the uneven distribution of electromagnetic waves of the electrode plates at the ultra-high frequency, in addition to assisting gas diffusion.

The material of the electrode plate 112 is selected from the group consisting of nickel, gold, silver, titanium, copper, palladium, stainless steel, beryllium copper alloy, aluminum, coated aluminum, and combinations thereof. In order to have a uniformly distributed RF electric field strength on the electrode plate 112, the impedance matching transmission lines 146 are symmetrically disposed on the edge or inside of the electrode plate 112. The distance between the impedance matching transmission line 146 and the electrode plate 112 from the center line of the electrode plate 112 needs to be equal. That is, the configuration of the impedance matching transmission lines 146 is to balance the difference in electric field strength so that the electric field strength distributed on the electrode plate 120 is the same.

The electrode plate has an area of between 10,000 square centimeters and 22,500 square centimeters. The surface of the electrode plate is surface treated. When the impedance matching transmission lines 146 are disposed at the edge of the electrode plate 112, the edge effects caused by the boundary conditions are changed due to the connection of the impedance matching transmission lines 146, and the electric field intensity distributed there is different from the inside of the electrode plate 112. . In the present invention, a surface treatment is provided on the edge region of the electrode plate 112 to change the surface roughness thereof to adjust the electromagnetic wave distribution on the electrode plate 112. The surface treatment method is selected from the group consisting of sandblasting, chemical etching, and anodizing. Surface treatment method in accordance with a preferred embodiment of the present invention Preferably, the surface roughness is controlled by grit blasting, and the surface roughness of the surface treatment is between 1 and 300 microns. The surface treatment area is located at the peripheral edge of the area of the electrode plate 112 and occupies one-twentieth to one-tenth of the area of the electrode plate 112.

The feed lines 122, 124 provide three or more different gases, and the three gas systems enter the reaction chamber at different times. In one embodiment, the first precursor A of step one and the inert gas of step two, such as nitrogen or argon, enter the gas inlet hole 125 of the reaction chamber 110 via the feed line 124, and enter the first A precursor A or an inert gas flows through the surface of the substrate 115 placed on the heating plate 114. The second precursor B of the third step enters the gas inlet hole 123 of the reaction chamber 110 via the feed line 122, and the second precursor B that enters forms an electricity between the electrode plate 112 and the heating plate 114. Slurry 116. The inert gas of step four may enter via feed line 122 or may enter the reaction chamber 110 via feed line 124. In each step, the action of venting the gas is accomplished by connecting the vent 127 to the vacuum pump 130 via the bleed line 126. In the present invention, in order to achieve the use of ultra-high frequency plasma and meet the requirements of the atomic layer deposition coating mechanism, the feed lines of the first precursor A and the second precursor B are different to avoid In the short time, the second precursor B cannot form a stable plasma. In addition, referring to FIG. 1 , for the stability of the flow field, the feed lines for the first precursor A and the second precursor B are disposed at different positions for the feed line of the first precursor A. 124 is substantially in the parallel direction of the electrode plate 112 and the heating plate 114, and the feed line 122 for the second precursor B is substantially perpendicular to the electrode plate 112 and the heating plate 114. The second precursor B enters the venting perforations of the electrode plate 112, and even after the diffusion plate, a stable and uniform plasma is rapidly formed between the electrode plate 112 and the heating plate 114.

Since the time of each cycle is very short and the gas entering the reaction chamber is very small, the control is very precise. A trace gas control valve is disposed on the feed lines 122, 124 to control access to the reaction chamber 110.

A plasma assisted atomic layer coating apparatus 100 of the present invention has the following effects:

1. For different frequency RF power, the number of transmission lines can be changed accordingly, thereby achieving the effect of reducing power reflection, providing stable power to the reaction cavity, thereby increasing the deposition thickness of each deposition cycle.

2. The electric field strength of the electrode plate is changed by the input path of the plurality of impedance matching transmission lines, thereby changing the distribution of the plasma, achieving a uniform plasma distribution pattern of a large area, and improving the uniformity of the deposited film.

While the present invention has been described in its preferred embodiments, it is not intended to limit the scope of the invention, and various modifications and changes can be made without departing from the spirit and scope of the invention. As explained above, various modifications and variations can be made without departing from the spirit of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

Claims (11)

A plasma assisted atomic layer coating device for a chemical vapor deposition system, comprising: a reaction chamber having a plurality of air inlet holes and an air outlet hole, wherein the reaction chamber is provided with an electrode plate and a heating plate, a plasma impedance, and the outer surface of the reaction chamber is grounded; a plurality of feed lines are connected to the plurality of air inlet holes; and a vacuum pump has a pumping line connected to the reaction chamber The venting port; and an RF module disposed outside the reaction chamber for providing an ultra-high frequency power to the reaction chamber; wherein the RF module includes an RF power source for providing the HF Frequency impedance; an impedance matching device electrically connected to the RF power source for adjusting the plasma impedance of the reaction chamber; a plurality of impedance matching transmission lines electrically connected between the impedance matching device and the electrode plate Having an impedance; the number of the impedance matching transmission lines is a power of 2, symmetrically distributed to the area of the electrode plate to evenly distribute the ultra high frequency power to the electrode plate; wherein the impedance matching The impedance of the transmission line is between 30 and 50 ohms, and the materials of the impedance matching transmission lines are selected from the group consisting of nickel, gold, silver, titanium, copper, palladium, stainless steel, beryllium copper alloy, aluminum, coated aluminum and combinations thereof. The group formed. The plasma assisted atomic layer coating apparatus of claim 1, wherein the frequency of the ultra high frequency power provided by the RF power source of the radio frequency module is 40.68 MHz. The plasma assisted atomic layer coating apparatus of claim 1, wherein the number of the impedance matching transmission lines is selected from one of 2, 4, and 8. The plasma assisted atomic layer coating apparatus of claim 1, wherein the impedance matching transmission lines have a impedance greater than a plasma impedance of the reaction chamber. The plasma assisted atomic layer coating device of claim 1, wherein the impedance matching transmission lines are coated with a layer of ceramic insulating material. The plasma assisted atomic layer coating apparatus according to claim 5, wherein the material of the ceramic insulating material is selected from the group consisting of cerium oxide, aluminum oxide, zirconium oxide, titanium oxide, and combinations thereof. The plasma assisted atomic layer coating apparatus of claim 1, wherein the feed lines provide three or more different gases, and the three gas systems enter the reaction chamber at different times. The plasma assisted atomic layer coating apparatus of claim 1, wherein the feed lines comprise a first feed line and a second feed line, the first feed line being on the electrode plate In a direction parallel to the heating plate, the second feed line is in a direction perpendicular to the electrode plate and the heating plate. The plasma assisted atomic layer coating apparatus of claim 1, wherein the electrode plate has a plurality of venting perforations and connects at least one of the plurality of air inlet holes. The plasma assisted atomic layer coating apparatus according to claim 1, wherein the electrode plate has an area of between 10,000 square centimeters and 22,500 square centimeters. The plasma assisted atomic layer coating device according to claim 1, wherein the electrode plate The surface is sandblasted.