CN115652417B - Device and method for optimizing epitaxial growth uniformity of thin film and epitaxial growth equipment - Google Patents
Device and method for optimizing epitaxial growth uniformity of thin film and epitaxial growth equipment Download PDFInfo
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Abstract
The invention discloses a device and a method for optimizing the epitaxial growth uniformity of a thin film and epitaxial growth equipment. The method comprises the following steps: the tray for bearing the substrate is enabled to do circular motion around a first axis and a second axis simultaneously, so that any point on the substrate does cycloidal motion along a non-circular track, and the quantities of raw materials deposited on different positions of the surface of the substrate are the same, wherein the first axis is the axis of the tray, and the second axis is parallel to and does not coincide with the first axis. The invention makes the surface points of the substrate do cycloidal motion, so that the surface points of the substrate can pass through more paths to cover a larger incident area of the beam current of the source furnace, and the incident distances from the source furnace to different positions on the surface of the substrate are basically kept constant after being averaged for multiple times, so that the incident fluxes at different positions on the surface of the substrate are basically the same, and the growth uniformity of the film is improved.
Description
Technical Field
The invention particularly relates to a device and a method for optimizing the epitaxial growth uniformity of a thin film and epitaxial growth equipment, and belongs to the technical field of epitaxial growth equipment.
Background
Molecular Beam Epitaxy (MBE) is a thin film growth technology based on a physical deposition method, and is characterized in that under an ultrahigh vacuum environment, elements forming a compound are respectively placed into different source furnaces, the source furnaces are heated, molecules (atoms) in the source furnaces are sprayed to the surface of a substrate at a certain thermal motion speed and beam intensity ratio, and deposition is carried out on the surface of the substrate heated to a certain temperature, so that thin film crystals grow.
Due to the difference of the relative angle and the spatial relative position of each source furnace, the growth uniformity of the thin film is seriously influenced. For the growth of a multi-layer material structure, the design target cannot be achieved due to the uneven thickness or components of the material in the growth process, the material performance and the device characteristics are affected, and the yield of the device is reduced. In addition, the doping elements, the composition ratios of different elements, and the non-uniform V/III ratio of the material may also affect the electrical or optical properties of the material, resulting in device performance that does not meet the design requirements and product yield reduction. The uniformity of epitaxial film growth depends on the incident flux of molecular (atomic) beams emitted by the source furnace beam to different positions on the surface of the substrate, namely the number of particles incident on a unit area in unit time, which is inversely related to the distance incident on the surface of the substrate.
At present, commercial MBE equipment adopts a mode that an MBE substrate tray autorotates and a substrate rotates along with a tray in a tray groove to improve the uniformity of material growth, the track generated when the substrate rotates is single, the track of a single point on a chip is circular, the injection area of a source furnace beam (molecular or atomic beam) cannot be covered in a large area, and the concentric rotating track of the substrate along with the tray hardly ensures the uniformity of the source furnace beam to different positions of the surface of the substrate due to the uneven distribution of the molecular beam on the substrate tray, so that the uniformity of material growth is hardly ensured.
FIG. 1a, FIG. 1b, FIG. 1c and FIG. 1d are schematic diagrams of film growth by using a conventional MBE apparatus, in which FIG. 1a and FIG. 1b show monolithic growth, FIG. 1c and FIG. 1d show multi-piece growth, source furnaces for supplying components are arranged around the lower part of a tray, the tray is rotated, and a substrate receives a source furnace flow from the source furnaces to perform material growth in a manner that the substrate rotates along with the tray in a tray groove of the tray. Because the relative angles of the source furnace and the substrate are different and the spatial relative positions are different, the incident fluxes of the component source furnaces to different positions of the substrate are also different, and finally, the component is not uniform, for example, al x Ga 1-x As has uneven element components, uneven doping and uneven V/III ratio, namely uneven As/Ga element ratio, and the like, thereby influencing the performance of the growing film material.
FIG. 2 is a schematic view of a growth model in the case of thin film growth using conventional MBE equipment, in which the path of the trajectory of the substrate is a single circle, the source furnace beam emitted from the source furnace is incident on different positions of the surface of the rotating substrate in the form of particle flow for deposition, and since the velocity of the source furnace beam is constant, the number of particles to be deposited on the surface of the substrate per unit time is inversely proportional to the square of the incident distance (the incident distance is the linear distance between the source furnace beam and the position where the source furnace beam is incident on the surface of the substrate) which is the same as the linear distance between the source furnace beam and the position where the source furnace beam is incident on the surface of the substrate)The density of particles deposited is higher, and the corresponding film thickness is thicker. Selecting any substrate as reference, assuming that the incident distance of the source furnace from the left edge of the substrate (the left edge in the figure) is L, and the radial angle with the substrate is L
The distance B from the radial direction of the substrate to the left incident edge (namely the distance from any point in the circular surface of the tray to the edge of the circular surface in the radial direction) is taken as a variable (B is more than or equal to 0 and less than or equal to d 1 ) Wherein d is 1 The diameter of the substrate, therefore, the distance C through which the right end of the source furnace beam is incident can be expressed as:
wherein L and
in relation to the initial installation position of the source furnace, it is generally arranged at a constant angle->
Is between 90 DEG and 180 DEG, so that according to the above formula it can be seen that C follows B (0. Ltoreq. B. Ltoreq. D) 1 ) The incident distance of the source furnace beam is gradually increased from left to right along the radial direction, but the incident speed is not changed, so the number of particles incident on a unit area per unit time is inversely proportional to the square of the distance, namely the film deposition thickness of the path with the farther incident distance is thinner, and the film thickness of the whole substrate is gradually thinner from left to right; illustratively, a particular set of values may be substituted herein when @>
At 90 degrees, when the diameter of the substrate is 1/2 of the incident distance L, the incident distance at the rightmost end is increased by about 11.8 percent compared with that at the leftmost end, namely, the nonuniformity of the thinnest part and the thickest part reaches about 19 percent, and the final performance of the material is difficult to ensureUniformity also satisfies this algorithm.
Therefore, how to optimize the growth uniformity of the molecular beam epitaxial film, that is, the tracks of the dots on the substrate cover the beam current spraying area through more paths, so that the incident fluxes from the source furnace to different positions of the substrate are basically the same, remains a technical problem to be solved in the industry.
Disclosure of Invention
The invention mainly aims to provide a device and a method for optimizing the epitaxial growth uniformity of a thin film and epitaxial growth equipment, so that the defects in the prior art are overcome.
In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:
the invention provides a method for optimizing the epitaxial growth uniformity of a film on one hand, which comprises the following steps: placing the substrate on a tray, and depositing raw materials required by the growth of the thin film material on the substrate in a particle flow mode so as to epitaxially grow the thin film material on the substrate; and, the method further comprises:
the tray for bearing the substrate is enabled to do circular motion around a first axis and a second axis simultaneously, so that any point on the substrate does cycloid motion along a non-circular track, and the amount of raw materials deposited on different positions of the surface of the substrate is the same, wherein the first axis is the axis of the tray, and the second axis is parallel to and not coincident with the first axis.
The invention provides a device for optimizing the epitaxial growth uniformity of a thin film, which comprises a tray and a source furnace, wherein the tray is arranged in a reaction chamber and is used for bearing a substrate, the source furnace is used for injecting components required by the growth of the thin film material to the substrate in the form of particle flow, and the device further comprises:
and the driving assembly is in transmission connection with the tray and is used for driving the tray to do circular motion around the first axis and the second axis simultaneously so as to enable any point on the substrate on the tray to do cycloidal motion along a non-circular track, so that the amounts of all components of the raw materials deposited on different positions of the surface of the substrate are the same, wherein the first axis is the axis of the tray, and the first axis and the second axis are parallel and do not coincide with each other.
The invention also provides epitaxial growth equipment which comprises the device for optimizing the epitaxial growth uniformity of the thin film.
Compared with the prior art, the method has the advantages that the surface points of the substrate are in cycloidal motion, so that the surface points of the substrate can pass through more paths to cover a larger incident area of the beam current of the source furnace, and the incident distances from the source furnace to different positions of the surface of the substrate are basically kept constant after being averaged for multiple times, so that the incident fluxes at different positions of the surface of the substrate are basically the same, and the growth uniformity of the film is improved.
Drawings
FIGS. 1a, 1b, 1c and 1d are schematic diagrams of a conventional MBE apparatus for thin film growth;
FIG. 2 is a schematic view of a growth model in thin film growth in a conventional MBE apparatus;
FIG. 3 is a schematic structural diagram of an apparatus for optimizing the uniformity of epitaxial growth of thin films according to embodiment 1 of the present invention;
FIGS. 4a and 4b are schematic diagrams illustrating the method for optimizing the uniformity of the epitaxial growth of the thin film according to the present invention;
fig. 5a, 5b, 5c, 5D, 5e, 5f, 5g, 5h, and 5i are simulated motion trajectory curves of the center M of the substrate three when the D/D ratio is 1.1, 1.2, 1.3, 1.4, 1.5, 2, 3, 4, and 5 in embodiment 1 of the present invention, respectively;
FIG. 6a is a circle center M of a third substrate and FIG. 6b is a motion trajectory curve of a circle center K of a second substrate optimized by the present invention;
FIG. 6c is a graph of the optimized simulated motion trajectory of the circle center M of the third substrate and the edge point V of the third substrate;
fig. 7a, fig. 7b, fig. 7c, fig. 7d, fig. 7e, fig. 7f, fig. 7g, fig. 7h, and fig. 7i are motion trajectory curves formed after the circle center M and an edge point V of the substrate three are located at the initial position and the rolling angles are 90 °, 180 °, 270 °, 360 °, 450 ° (i.e., the 90 ° position of the second turn), 540 °, 630 °, and 720 °, respectively;
fig. 8a and 8b are schematic structural diagrams of an apparatus for optimizing the uniformity of epitaxial growth of a thin film provided in embodiment 2 of the present invention.
Detailed Description
In view of the deficiencies in the prior art, the inventors of the present invention have made extensive studies and extensive practices to provide technical solutions of the present invention. The technical solution, its implementation and principles, etc. will be further explained as follows.
The invention provides a method for optimizing the epitaxial growth uniformity of a film on one hand, which comprises the following steps: placing the substrate on a tray, and depositing raw materials required by the growth of the thin film material on the substrate in a particle flow mode so as to epitaxially grow the thin film material on the substrate; and, the method further comprises:
the tray for bearing the substrate is enabled to do circular motion around a first axis and a second axis simultaneously, so that any point on the substrate does cycloidal motion along a non-circular track, and the quantities of raw materials deposited on different positions of the surface of the substrate are the same, wherein the first axis is the axis of the tray, and the second axis is parallel to and does not coincide with the first axis.
In a specific embodiment, the method for optimizing the uniformity of the epitaxial growth of the thin film comprises the following steps: moving (rolling) the tray along a set circular track in three-dimensional space to make any point E (x) on the substrate 1 ，y 1 ，z 1 ) Following a trajectory as shown in the following system of equations:
wherein the axis of the set circular trajectory is a second axis, k = D/D, t = D 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate,
is the angle through which any point P on the edge profile of the tray turns.
In a specific embodiment, the optimizationThe method for the epitaxial growth uniformity of the thin film comprises the following steps: enabling the tray to rotate in a first direction around a first axis in a three-dimensional space, and enabling the tray to rotate along a set circular track around a second axis along the first direction so as to enable any point E (x) on the substrate to rotate 1 ，y 1 ，z 1 ) Following a trajectory as shown in the following system of equations:
wherein the axis of the set circular track is a second axis, the tray is tangent to the set circular track, and t = d 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate,
for angular speed of rotation of the tray about the second axis, in combination with a motor>
For the angular speed at which the tray rotates about the first axis, is greater or less than>
The rotation time of the tray.
In a specific embodiment, the method for optimizing the uniformity of the epitaxial growth of the thin film comprises the following steps: enabling the tray to rotate around a first axis in a three-dimensional space along a first direction, and enabling the tray to rotate around a second axis along a set circular track along a second direction so as to enable any point E (x) on the substrate to rotate 1 ，y 1 ，z 1 ) Moves along a trajectory shown by the following system of equations:
wherein the axis of the set circular trajectory is a second axis, andthe tray is tangent to the set circular track, the first direction and the second direction are opposite, and t = d 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate,
for the angular speed of the rotation of the tray about the second axis>
For the angular speed at which the tray rotates about the first axis, is determined>
Is the rotation time of the tray.
The invention provides a device for optimizing the epitaxial growth uniformity of a thin film, which comprises a tray and a source furnace, wherein the tray is arranged in a reaction chamber and is used for bearing a substrate, the source furnace is used for injecting components required by the growth of the thin film material to the substrate in the form of particle flow, and the device further comprises:
and the driving assembly is in transmission connection with the tray and is used for driving the tray to do circular motion around the first axis and the second axis simultaneously so as to enable any point on the substrate on the tray to do cycloid motion along a non-circular track, so that the amounts of raw materials deposited on different positions of the surface of the substrate are the same, wherein the first axis is the axis of the tray, and the first axis and the second axis are parallel and do not coincide with each other.
In a specific embodiment, the driving assembly comprises a guide wheel and a first driving mechanism, the guide wheel is fixedly arranged, the tray is movably matched with the circumferential side surface of the guide wheel and is in transmission connection with the first driving mechanism, and the tray can roll along a set circular track on the circumferential side surface of the guide wheel under the driving of the first driving mechanism, so that any point E (x) on the substrate on the tray can roll 1 ，y 1 ，z 1 ) Following a trajectory as shown in the following system of equations:
wherein k = D/D, t = D 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate,
the second axis is the axis of the guide wheel and the set circular track, which is the angle rotated by any point P on the edge profile of the tray. />
Further, the guide wheel is in transmission fit with the tray in a meshing mode.
Further, the tray and the guide wheel are sequentially arranged along the radial direction of the tray, the tray is arranged on the outer side or the inner side of the guide wheel, and the set circular track is located on the inner ring surface of the guide wheel.
In a specific embodiment, the driving assembly includes a first driving mechanism and a second driving mechanism, the first driving mechanism and the second driving mechanism are both in transmission connection with the tray, the first driving mechanism is used for driving the tray to rotate around a first axis along a first direction, the second driving mechanism is used for driving the tray to rotate around a second axis along a set circular track along the first direction, so that any point E (x) on the substrate can rotate along the first direction 1 ，y 1 ，z 1 ) Following a trajectory as shown in the following system of equations:
wherein the second axis is the axis of the set circular track, the tray is tangent to the set circular track, and t = d 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate,
for the angular speed of the rotation of the tray about the second axis>
For the angular speed at which the tray rotates about the first axis, is greater or less than>
The rotation time of the tray.
In a specific embodiment, the driving assembly includes a first driving mechanism and a second driving mechanism, both of which are in transmission connection with the tray, the first driving mechanism is used for driving the tray to rotate around a first axis along a first direction, the second driving mechanism is used for driving the tray to rotate around a second axis along a set circular track and a second direction, so that any point E (x) on the substrate can rotate along the set circular track and the second direction 1 ，y 1 ，z 1 ) Following a trajectory as shown in the following system of equations:
wherein the second axis is the axis of the set circular track, the tray is tangent to the set circular track, the first direction and the second direction are opposite, and t = d 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate,
for the angular speed of the rotation of the tray about the second axis>
For the angular speed at which the tray rotates about the first axis, is determined>
When the tray is rotatedAnd (3) removing the solvent.
The invention also provides epitaxial growth equipment which comprises the device for optimizing the epitaxial growth uniformity of the thin film.
Further, the epitaxial growth apparatus comprises a molecular beam epitaxy apparatus.
The technical solution, the implementation process and the principle thereof will be further explained with reference to the drawings and specific embodiments, and unless otherwise specified, the reaction chamber, the source furnace, the heating device, the driving motor, etc. in the molecular beam epitaxy apparatus in the embodiment of the present invention are all known to those skilled in the art, and the specific apparatus model and structure thereof are not limited herein.
Example 1
Referring to fig. 3, an epitaxial growth apparatus includes a reaction chamber, a plurality of source furnaces 6, a gear 1, a tray 2, and a first driving mechanism 4, where the gear 1, the tray 2, and the source furnaces are disposed in the reaction chamber, the gear 1 is fixed, the tray 2 is engaged with the gear 1 and is matched to form a gear pair, the first driving mechanism 4 is in transmission connection with the tray 2, the tray 2 can rotate around a first axis 10 in a first direction under the driving of the first driving mechanism 4, and meanwhile, in the self-rotation process of the tray 2, through the engagement transmission between the tray 2 and the gear 1, the tray 2 also makes a pure rolling motion around a set circular track on a circumferential side surface of the gear 1, that is, the tray 2 also makes a circular motion around a second axis 20.
In this embodiment, the gear 1 and the tray 2 are both circular structures, the axis of the tray 2 is a first axis 10, the axis of the gear 1 is a second axis 20, meanwhile, the second axis 20 is also the axis of the set circular track, the first axis 10 and the second axis 20 are parallel to each other and do not coincide with each other, and specifically, the first axis and the second axis are arranged at intervals in the radial direction of the gear/tray.
In the present embodiment, a first gear tooth structure is provided on a circumferential side surface (i.e., a circumferential surface) of the tray 2; a second gear tooth structure is arranged on the circumferential side surface (namely the circumferential surface) of the gear 1, the first gear tooth structure is meshed with the second gear tooth structure to form a gear pair, and when the tray 2 rotates around the first axis, the first gear tooth structure can be always kept in a meshed state with the second gear structure to enable the tray 2 to roll along a set circular track on the circumferential side surface of the gear 1.
In this embodiment, the gear 1 is a circular ring structure, an inner annular surface of the gear 1 encloses to form a circular opening structure, an axis of the opening structure is the second axis, the second gear tooth structure is disposed on the inner annular surface of the gear 1, that is, the gear is a ring gear, the tray 2 is disposed in the opening structure, and a diameter of the tray 2 is smaller than a diameter of the opening structure, that is, the set circular track is located on the inner annular surface of the gear 1.
In this embodiment, the tray 2 is used for carrying substrates required for epitaxial growth, one or more tray slots for placing the substrates are arranged on the tray 2, and a plurality of the tray slots are sequentially arranged along the circumferential direction of the tray, wherein the diameter d of the tray 2 depends on the model of epitaxial growth equipment such as MBE, and the tray 2 is a series of standard models such as 2 inches, 4 inches, 6 inches, and the like.
In this embodiment, the set circular trajectory is located on the inner ring surface of the gear 1, and the diameter of the set circular trajectory may be approximately equal to the inner ring diameter of the gear with a circular structure.
In the present embodiment, the first driving mechanism 4 is a rotation driving mechanism, and may be, for example, a rotation driving motor.
In this embodiment, the tray 2 is driven by the first driving mechanism 4 to rotate around the first axis, and through gear transmission with the gear 1, the tray 2 makes pure rolling motion along the inner ring surface of the gear 1, and the motion track of any point on the surface of the substrate on the tray 2 is a non-circular track, so that the track of the surface point of the substrate can pass through more paths to cover a larger source furnace beam incident area, and the incident flux of each raw material component deposited on different positions of the surface of the substrate is kept the same, thereby realizing the uniform growth of the thin film on the substrate.
In this embodiment, the motion trajectory of any point on the surface of the substrate depends on the ratio of D to D, and taking MBE epitaxial growth equipment as an example, since the placement position and the incident angle of the source furnace are fixed values, it is only necessary to calculate the optimal D value, so as to optimize the uniformity of the thickness of the film grown on the substrate.
In this embodiment, please refer to fig. 4a, when the epitaxial growth apparatus in the embodiment of the present invention performs the thin film epitaxial growth by the MBE process, in the reaction chamber, a plurality of source furnaces 6 for providing components required for the thin film growth are disposed around the tray 2, and the source furnaces 6 provide raw materials required for the thin film growth, and the tray 2 not only rotates around its own self-rotation, but also performs a pure rolling motion along a set circular track on the inner annular surface of the gear 1.
In the embodiment, the source furnace 6 is arranged below the tray 2 along the first axial direction, the tray 2 drives the substrate 3 to move, the center (i.e. the circle center) of the gear 1 is taken as the origin O of the three-dimensional coordinate system, and the coordinate of the injection point a of the source furnace 6 in the three-dimensional coordinate system is assumed as
The coordinate of any point E on a certain substrate 3 is (` er `)>
During the movement of the tray 2, point E is defined by point E 1 The point will move to E 2 The position of the point, at this time, the incident flux of the particle flow ejected from the source furnace at the point E at any point will change, and since the incident flux of the particle flow is inversely proportional to the square of the incident distance, only the distance from the point a to the point E needs to be calculated, please refer to fig. 4b, the motion of the tray 2 is that the small circle (tray) makes a pure rolling motion around the large circle (a set circular track on the inner ring surface of the gear), the ratio of the diameter D of the large circle to the diameter D of the small circle is k, any point P (x, y, z) on the edge of the tray is taken, in the process that the tray moves around the first axis of the tray, the point P makes a cycloidal motion, and the trajectory equation of the point P at this time is equation 1):
Wherein the content of the first and second substances,
is the angle through which point P is rotated.
In this embodiment, the center of the substrate 3 is O', and any point E (x) in the substrate 3 is 1 ，y 1 ，z 1 ) A linear distance O 'E = d from the center O' of the substrate 1 For the same reason, the trajectory equation of any point E in the substrate 3 can be obtained as equation 2):
Wherein t = d 1 /d。
Specifically, the incident distance C from the injection point a of the source furnace 6 to the point E in the substrate 3 is:
Substituting equation 3) into equation 2) and simplifying to obtain equation 4):
thereby obtaining the average value of the incident distance from the injection point A of the source furnace to any point E in the substrate
Comprises the following steps:
Wherein F is the first five constant terms in the formula 4),
for the last 3 expression, T is the selected period, the average of the calculated incident distances can be simplified to equation 6); of course, it can be easily seen by observation (here 1)<k<2，0<t<1, and d is less than x 0 ，y 0 ，z 0 Any one of the above) is a trigonometric periodic function, and the coefficient of each of the latter three terms is much smaller than the sum of the first five constant terms, so that the average value of the latter three terms is much smaller than the average value of the first five terms, which is negligible, and the average value of the incident distance C can be reduced to equation 6):
Wherein x is 0 、y 0 、z 0 The coordinate value of the incident point A of the source furnace is related to the installation position and is a constant; k = D/D (i.e. the ratio of the large diameter D to the small diameter D, where D is variable); t = d 1 D (i.e., the ratio of the distance between the point E on the substrate and the center of the substrate to the radius of the tray).
From the above, it can be understood that the injection distance from the injection point A of the source furnace to any point E in the substrate on the tray only changes with the change of t, and t = d 1 Carry over existing MBE data (0.16)<t<0.85 Based on this), the unevenness of the film grown on the substrate is only 1/20 of the unevenness of the film grown by the conventional MBE epitaxial growth apparatus, that is, the unevenness is better than 1%. Therefore, the invention greatly optimizes the uniformity of film growth, and x can be increased according to the actual engineering design 0 、y 0 、z 0 Specific gravity of (d) is reduced 2 t 2 The specific gravity of (a) can further optimize the uniformity of film growth.
Specifically, after the source furnace is installed and the molecular beam flow velocity is determined, the incident trajectory of the raw material sprayed from the source furnace is in a spherical wave state, the number of particles incident on the surface of the substrate is inversely proportional to the square of the distance, and the variation ratio of the incidence distance at the maximum and minimum positions is calculated,so increase x 0 、y 0 、z 0 Specific gravity of (1), corresponding to d 2 t 2 The function change has little influence on the total amount, and the growth uniformity can be greatly optimized.
Similarly, for source furnaces with different incident angles and different spatial positions, although the incident distances are different, the incident distances to all points on each substrate are stable constants, and by setting the initial source furnace beam injection speed of each source furnace, the doping uniformity and the uniformity of different component elements in the material growth process can be well ensured.
The result of the invention is verified and a motion trajectory curve for optimizing the film growth uniformity is provided by simulating a trajectory curve of a tray which makes pure rolling motion around a great circle (namely a set circular trajectory on the inner ring surface of a gear), wherein the tray is provided with four substrates, the four substrates are a substrate I, a substrate II, a substrate III and a substrate IV in sequence along the anticlockwise direction, the central point of the substrate II is K, the central point of the substrate III is M, and any edge point of the substrate III is V.
Fig. 5a, 5b, 5c, 5D, 5e, 5f, 5g, 5h, and 5i are simulated motion trajectory curves of the center M of the substrate three on the tray in embodiment 1 of the present invention when the D/D ratio is 1.1, 1.2, 1.3, 1.4, 1.5, 2, 3, 4, and 5, respectively. By comparing the simulation results, it can be known that when the tray performs rolling motion along a set circular track on the inner annular surface of the gear, the motion track of the point on the substrate is only related to the ratio of the diameter D of the gear to the diameter D of the tray. And when D/D is an integer, the motion trail of the point on the substrate is a curve similar to a polygon, the number of the polygon sides is equal to the integer value of the D/D, and all trail paths can be completed only by rolling the tray for one circle. And when the D/D is not an integer, the D/D is converted into a simplest formula m/n (m and n are prime), wherein m represents the number of motion track curves of points on the substrate, n represents the number of turns of rolling motion of the tray, so that the number m of all the motion track curves can be obtained, and the more dense the finally optimized motion track curve is, the better the result is.
FIG. 6a is a graph showing the movement trace of the center M of the third substrate and the center K of the second substrate in FIG. 6b after being optimized according to the present invention, where the M point and the K point have the same O point according to the calculation result ’ E/d is a value t, so that the motion trail curves of the two are completely the same, and the simulation results shown in the figures 6a and 6b also verify the correctness of the calculation; fig. 6c shows a simulated motion trajectory curve loc5 of the center M of the third substrate and a simulated motion trajectory curve loc4 of the three edge points V of the substrate.
Fig. 7a, 7b, 7c, 7d, 7e, 7f, 7g, 7h, and 7i are simulated motion trajectory curves formed during the process that the center M of the circle of the substrate three and any edge point V roll with the tray for one circle in the embodiment of the present invention, respectively, where the dotted line in the graph is the motion trajectory curve loc4 of the edge point V, and the solid line is the motion trajectory curve loc5 of the center M, where fig. 7a is a schematic diagram of the state that the center M of the circle of the substrate three and any edge point V are located at the initial position (the trajectory in the graph is a trajectory curve after the circle has been rotated, and fig. 7b, 7c, 7d, and 7e are all diagrams); fig. 7b, fig. 7c, fig. 7D, fig. 7e, fig. 7f, fig. 7g, fig. 7h, and fig. 7i are motion trajectory curves formed after the center M of the substrate three and an edge point V roll by angles of 90 °, 180 °, 270 °, 360 °, 450 ° (i.e., 90 ° position of the second circle), 540 °, 630 °, and 720 °, respectively, and it can be seen from the figures that the trajectory points M and V swing back and forth around the center D1 of the tray and the center of the large circle that rolls, and the incident distances thereof change continuously, but after multiple averaging, the incident distance of any point on the substrate approaches a stable constant, and the numerical difference is very small, so that the uniformity of the incident beam of the source oven can be well ensured.
Example 2
Referring to fig. 8a and 8b, the epitaxial growth apparatus in this embodiment has substantially the same structure as that in embodiment 1, and the same parts are not described again here, where the difference between the two parts is: the epitaxial growth equipment in this embodiment cancels a gear and adds a second driving mechanism 5, the second driving mechanism 5 is in transmission connection with the tray 2 and is used for driving the tray 2 to rotate around a second axis along a set circular track, a first direction or a second direction, that is, the tray 2 rotates under the driving of the first driving mechanism 4 and revolves around the second axis under the driving of the second driving mechanism 5, and similarly, the substrate 3 on the tray 2 can realize a movement mode of rotation plus revolution, and the movement track of any point in the substrate 3 on the tray 2 is also a cycloid movement track.
In this embodiment, when the tray 2 is driven to rotate by the first driving mechanism and the second driving mechanism at the same time, the motion locus of any point P (x, y, z) on the peripheral edge of the tray 2 is as follows:
and when the direction of the tray rotating around the first axis is the same as the direction of the tray rotating around the second axis, any point E (x) on the substrate on the tray 1 ，y 1 ，z 1 ) The following tracks are followed:
when the direction of the tray rotating around the first axis is opposite to the direction of the tray rotating around the second axis, any point E (x) on the substrate on the tray 1 ，y 1 ，z 1 ) The motion trajectory satisfies the equation set as follows:
wherein the second axis is the axis of the set circular track, the tray is tangent to the set circular track, k = D/D, t = D 1 D, D is the diameter of the tray, D is the diameter of the set circular trajectory,
angle of rotation of point P, d 1 Is the linear distance between point E and the center of the substrate, is based on the value of the square>
For the angular speed of the rotation of the tray about the second axis>
For the angular speed at which the tray rotates about the first axis, is determined>
The rotation time of the tray.
The principle of achieving uniform growth of the thin film in this embodiment is substantially the same as that in embodiment 1, and is not described herein again.
It should be noted that a series of components such as gears and motors adopted by the invention can be made of stainless steel materials, the selected motor is a vacuum high-temperature special motor, the lubrication mode of the related moving parts is dry lubrication, impurities are not volatilized at the vacuum high temperature, the cleanness of a cavity can be ensured, and the use requirement of MBE equipment is met.
The technical idea of the invention is not only suitable for the tray adapted to four pieces of substrates in the example, but also meets the requirements of other substrates with different sizes and different quantities.
Of course, the device structure in the present invention is not limited to the structure in embodiment 1 and embodiment 2, and it is within the scope of the present invention to optimize the uniformity of the thin film growth by using the principle of cycloid motion for other devices.
The device for optimizing the epitaxial growth uniformity of the film has the advantages of simple structure, reliable performance and lower cost, and can realize the uniform growth of the molecular beam epitaxial film; the invention makes the surface points of the substrate do cycloidal motion, so that the surface points of the substrate can pass through more paths to cover a larger incident area of the beam current of the source furnace, and the incident distances from the source furnace to different positions on the surface of the substrate are basically kept constant after being averaged for multiple times, thereby ensuring that the amount of raw materials deposited to different positions on the surface of the substrate is the same, and further improving the growth uniformity of the film.
It should be understood that the above-mentioned embodiments are merely illustrative of the technical concepts and features of the present invention, which are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and therefore, the protection scope of the present invention is not limited thereby. All equivalent changes and modifications made according to the spirit of the present invention should be covered in the protection scope of the present invention.
Claims (9)
1. A method of optimizing the uniformity of epitaxial growth of a thin film, comprising: placing the substrate on a tray, and depositing raw materials required by the growth of the thin film material on the substrate in a particle flow mode so as to epitaxially grow the thin film material on the substrate; characterized in that the method further comprises:
making a tray carrying the substrate do circular motion around a first axis and a second axis simultaneously, and making the tray move along a set circular track in a three-dimensional space, so that any point on the substrate does cycloidal motion along a non-circular track, thereby making the amount of raw materials deposited on different positions of the surface of the substrate the same, and any point E (x) on the substrate 1 ，y 1 ，z 1 ) Is shown along the following equation system:
the first axis is the axis of the tray, the axis of the set circular track is the second axis, the second axis and the first axis are parallel and do not coincide with each other, the tray is tangent to the set circular track, k = D/D, and t = D 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate, alpha is the angle rotated by any point P on the edge profile of the tray, 1<k<2。
2. A method of optimizing the uniformity of epitaxial growth of a thin film, comprising: placing the substrate on a tray, and depositing raw materials required by the growth of the thin film material on the substrate in a particle flow mode so as to epitaxially grow the thin film material on the substrate; characterized in that the method further comprises:
enabling the tray to rotate around a first axis in a first direction in a three-dimensional space, and enabling the tray to rotate around a second axis along a set circular track and the first direction at the same time, so that any point on the substrate makes cycloidal motion along a non-circular track, the quantities of raw materials deposited on different positions of the surface of the substrate are the same, and any point E (x) on the substrate is the same 1 ，y 1 ，z 1 ) Is shown along the following equation system:
the first axis is the axis of the tray, the axis of the set circular track is the second axis, the tray is tangent to the set circular track, k = D/D, and t = D 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate,
for angular speed of rotation of the tray about the second axis, in combination with a motor>
For the angular speed at which the tray rotates about the first axis, is greater or less than>
For the rotation time of the tray, 1<k<2。
3. A method of optimizing the uniformity of epitaxial growth of a thin film, comprising: placing the substrate on a tray, and depositing raw materials required by the growth of the thin film material on the substrate in a particle flow mode so as to epitaxially grow the thin film material on the substrate; characterized in that the method further comprises:
enabling the tray to rotate around a first axis in a first direction in a three-dimensional space, enabling the tray to rotate around a second axis in a set circular track and a second direction at the same time, enabling any point on the substrate to do cycloidal motion along a non-circular track, and enabling the amount of raw materials deposited on different positions of the surface of the substrate to be the same, wherein any point E (x) on the substrate is the same 1 ，y 1 ，z 1 ) Is shown along the following equation system:
the first axis is the axis of the tray, the second axis is the axis of the set circular track, the second axis and the first axis are parallel and do not coincide, the tray is tangent to the set circular track, the first direction and the second direction are opposite, k = D/D, and t = D 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate,
for the angular speed of the rotation of the tray about the second axis>
For the angular speed at which the tray rotates about the first axis, is determined>
For the rotation time of the tray, 1<k<2。
4. An apparatus for optimizing the uniformity of epitaxial growth of thin films, comprising a tray disposed within a reaction chamber, the tray for carrying a substrate, and a source furnace for impinging components required for the growth of thin film materials onto the substrate in the form of a stream of particles, the apparatus comprising:
drive assemblyThe drive assembly comprises a guide wheel and a first drive mechanism, the guide wheel is fixedly arranged, the tray is movably matched with the circumferential side face of the guide wheel, the tray is connected with the first drive mechanism in a transmission mode and can drive the first drive mechanism to drive the second drive mechanism to drive the first drive mechanism to rotate along a set circular track on the circumferential side face, the tray is made to do circular motion around a first axis and a second axis simultaneously, any point on a substrate on the tray is made to do cycloidal motion along a non-circular track, and accordingly the amount of each component of raw materials deposited on different positions of the surface of the substrate is the same, and any point E (x) on the substrate on the tray is made to be the same 1 ，y 1 ，z 1 ) Moves along a trajectory shown by the following system of equations:
wherein the first axis is the axis of the tray, the first axis and the second axis are parallel to each other and are not coincident, k = D/D, t = D 1 D, D is the diameter of the tray, D is the diameter of the set circular path, D 1 Is the linear distance between the point E and the center of the substrate circle, alpha is the angle rotated by any point P on the edge profile of the tray, and the second axis is the guide wheel and the axis of the set circular track, 1<k<2。
5. The apparatus for optimizing thin film epitaxial growth uniformity of claim 4, wherein: the guide wheel is in transmission fit with the tray in a meshing mode.
6. Apparatus for optimizing thin film epitaxial growth uniformity according to claim 4 or 5, characterized in that: the tray and the guide wheel are sequentially arranged along the radial direction of the tray, the tray is arranged on the inner side of the guide wheel, and the set circular track is located on the inner annular surface of the guide wheel.
7. An apparatus for optimizing the uniformity of epitaxial growth of thin films, comprising a tray disposed within a reaction chamber, the tray for carrying a substrate, and a source furnace for impinging components required for the growth of thin film materials onto the substrate in the form of a stream of particles, the apparatus comprising:
drive assembly, drive assembly includes first actuating mechanism and second actuating mechanism, first actuating mechanism and second actuating mechanism all with the tray transmission is connected, first actuating mechanism is used for ordering about the tray coils first axis and follows first direction autogyration, second actuating mechanism is used for ordering about the tray rotates along a circular orbit of settlement, first direction around the second axis, and makes any point on the substrate that is located the tray be cycloid motion along a non-circular orbit to make the volume of each component of the raw materials of deposiing to the different positions in substrate surface the same, any point E (x) on the substrate that is located the tray 1 ，y 1 ，z 1 ) Following a trajectory as shown in the following system of equations:
wherein the first axis is the axis of the tray, the second axis is the axis of the set circular track, the tray is tangent to the set circular track, k = D/D, t = D 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate,
for the angular speed of the rotation of the tray about the second axis>
For the angular speed at which the tray rotates about the first axis, is determined>
For the rotation time of the tray, 1<k<2。
8. An apparatus for optimizing the uniformity of epitaxial growth of thin films, comprising a tray disposed within a reaction chamber, the tray for carrying a substrate, and a source furnace for impinging components required for the growth of thin film materials onto the substrate in the form of a stream of particles, the apparatus comprising:
drive assembly, drive assembly includes first actuating mechanism and second actuating mechanism, first actuating mechanism and second actuating mechanism all with the tray transmission is connected, first actuating mechanism is used for ordering about the tray coils first axis and follows first direction autogyration, second actuating mechanism is used for ordering about the tray rotates along a circular orbit of settlement, second direction around the second axis, and makes any point on the substrate that is located the tray be cycloid motion along a non-circular orbit to make the volume of each component of the raw materials of deposiing to the different positions in substrate surface the same, any point E (x) on the substrate that is located the tray 1 ，y 1 ，z 1 ) Following a trajectory as shown in the following system of equations:
wherein the first axis is the axis of the tray, the second axis is the axis of the set circular track, the tray is tangent to the set circular track, the first direction is opposite to the second direction, k = D/D, t = D 1 D, D is the diameter of the tray, D is the diameter of the set circular track, D 1 Is the linear distance between point E and the center of the substrate,
for angular speed of rotation of the tray about the second axis, in combination with a motor>
For the angular speed at which the tray rotates about the first axis, is determined>
For the rotation time of the tray, 1<k<2。
9. An epitaxial growth apparatus, characterized by comprising an apparatus for optimizing the epitaxial growth uniformity of thin films according to any one of claims 4 to 8, said epitaxial growth apparatus comprising a molecular beam epitaxy apparatus.
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| JP6017817B2 (en) * | 2011-12-15 | 2016-11-02 | 住友化学株式会社 | Surface treatment apparatus, surface treatment method, substrate support mechanism, and program |
| CN103820769B (en) * | 2012-11-16 | 2016-08-31 | 北京北方微电子基地设备工艺研究中心有限责任公司 | A kind of reaction chamber and MOCVD device |
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| CN105386121B (en) * | 2015-10-22 | 2018-05-15 | 中国电子科技集团公司第四十八研究所 | Planetary rotation device for silicon carbide epitaxial growth |
| CN112080735A (en) * | 2020-10-12 | 2020-12-15 | 佛仪科技(佛山)有限公司 | Tray device for vapor chemical deposition |
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