A vacuum sample stage heating device with self-compensation of temperature field

Abstract

The application discloses a kind of temperature field self-compensating vacuum sample stage heating device, mainly include 5 parts, inner ring heating sheet, main heating sheet one, main heating sheet two, main heating sheet three, outer ring heating sheet.The deformation self-compensation of the heater structure designed in the application can balance the overall shift of heating temperature field caused by high temperature deformation.In addition, by adjusting the heating power relationship of main heating sheet one, main heating sheet two and main heating sheet three, and then optimizing the heating power of inner ring heating sheet and outer ring heating sheet, high temperature temperature uniformity on sample stage tray can be realized.The heating device of the application can be easily realized size expansion, especially suitable for uniform heating of multi-piece large-size epitaxial growth system.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of thin film preparation, and particularly relates to a vacuum sample table heating device with self-compensated temperature field. BACKGROUND

[0002] Molecular beam epitaxy is a high-precision thin film preparation technology. In a vacuum chamber, atomic or molecular beam of source material is deposited on an epitaxial substrate at a certain temperature to form a thin film with certain crystal quality, material composition and thickness. Since molecular beam epitaxy can prepare atomic-level thin films, the growth rate is very slow, and early molecular beam epitaxy is mainly used in the field of scientific research. In recent years, with the increasingly wide application of molecular beam epitaxy technology, industrial production needs molecular beam epitaxy equipment for multiple pieces and large-size substrates.

[0003] With the increase of the size of the sample table in the molecular beam epitaxy equipment, the problem of temperature uniformity on the substrate surface becomes more and more important. Especially when growing material layers that are sensitive to temperature, the non-uniformity of temperature will make the material properties of the grown thin film material, such as growth rate, material composition and crystal quality, non-uniform, which greatly reduces the effective utilization area of the epitaxial film, that is, reduces the yield of subsequent chips. In addition, severe temperature non-uniformity can even cause large-area waste pieces. During the operation of the conventional mosquito incense type heater at high temperature, the whole body produces extension deformation in the radial direction, causing the temperature field of the heater to shift outward, and thus leading to different growth temperatures and changes in the temperature distribution on the substrate surface. Therefore, it is very important to design a sample table heating system with uniform heating to promote the development of multiple-piece and large-size molecular beam epitaxy equipment. SUMMARY

[0004] The present application provides a molecular beam epitaxy vacuum sample table heating system with uniform heating. Through structural self-compensation, the problem of outward shift of the heating temperature field caused by high-temperature deformation of the heater material in multiple-piece and large-size molecular beam epitaxy equipment can be compensated.

[0005] The heater of the molecular beam epitaxy sample table heating system with uniform heating provided by the present application comprises five parts, which are, from inside to outside, an inner ring heating sheet, a main heating sheet one, a main heating sheet two, a main heating sheet three and an outer ring heating sheet. The main heating sheet two is formed by connecting circular arc heating sheets of the same diameter size in sequence, and the geometric tangent lines at the connection points of adjacent two circular arc heating sheets coincide. The main heating sheet one and the main heating sheet two are formed by connecting circular arc heating sheets of two different diameters in sequence in the order of small circular arc and large circular arc, and the geometric tangent lines at the connection points of adjacent two circular arc heating sheets coincide.

[0006] The adjacent arcs of the main heating sheet one, the main heating sheet two and the main heating sheet three along the radial direction are concentric circles, the small arc radius of the main heating sheet one is the same as the small arc radius of the main heating sheet three, and the large arc radius of the main heating sheet one is the same as the large arc radius of the main heating sheet three. The vertical normal distance of the arc of the main heating sheet one and the main heating sheet two is equal to the vertical normal distance of the arc of the main heating sheet two and the main heating sheet three, and the distance range is 5mm-10mm.

[0007] Further, the heating sheet thicknesses of the inner ring heating sheet, the main heating sheet one, the main heating sheet two, the main heating sheet three and the outer ring heating sheet are the same, and the thickness range is 0.5mm-1.5mm; the heating sheet widths of the main heating sheet one, the main heating sheet two and the main heating sheet three are the same, and the width range is 2mm-10mm; the heating sheet widths of the inner ring heating sheet and the outer ring heating sheet are the same, and the width of the inner ring heating sheet is 1.5-3 times the width of the main heating sheet one.

[0008] In addition, the heating powers of the inner ring heating sheet and the outer ring heating sheet are independently controlled. The heating powers of the main heating sheet one, the main heating sheet two and the main heating sheet three are coupled with each other, and the coupling relationship is that the heating power of the main heating sheet one is P1, the heating power of the main heating sheet two is P2, and the heating power of the main heating sheet three is P3, then P1=a+bP2; P3=c+dP2, wherein the parameter values of a and c are determined by the structure and material parameters of the heater, and the parameter values of b and d are determined by the target temperature of the heater.

[0009] When the heating system rises to high temperature, the heating sheet is elongated due to thermal expansion and contraction, and the arc radius is increased. Therefore, the overall outward deviation of the temperature field can be greatly reduced in a self-compensation manner because the expansion directions of the adjacent two arcs are opposite. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 and Figure 2 is a schematic view showing the heater according to the present application. Figure 3 is a schematic view showing the heater according to the present application. Figure 4 is a schematic view showing the heater according to the present application.

[0011] Explanation of reference numerals in the attached drawings: 101 Substrate pit one, 102 Substrate pit two, 103 Substrate pit three, 104 Substrate pit four, 105 Substrate tray, 200 Heating element, 201 Outer ring heating element, 202 Main heating element one, 203 Main heating element two, 204 Main heating element three, 205 Inner ring heating element, 206 Outer ring heating element electrode, 207 Inner ring heating element electrode, 208 Main heating element three electrode, 209 Main heating element two electrode, 210 Main heating element three electrode, 211 Rotating shaft, 301 Reflector one, 302 Ceramic pad one, 303 Ceramic pad two, 304 Ceramic pad three, 401 Reflector two, 402 Connecting support one, 404 Connecting support two. Detailed Implementation

[0012] Example 1: As Figures 1-4 As shown, a vacuum sample stage heating system suitable for four 4-inch epitaxial wafers is provided. The heating section comprises five parts, from the inside out: an inner heating element 205, a first main heating element 202, a second main heating element 203, a third main heating element 204, and an outer heating element 201. The second main heating element 203 is formed by sequentially connecting arc-shaped heating elements of the same diameter, with the geometric tangents of adjacent arc-shaped heating elements coinciding at the connection point. The first and third main heating elements 202 and 204 are formed by sequentially connecting arc-shaped heating elements of two different diameters in the order of small arc / large arc / small arc / large arc…, with the geometric tangents of adjacent arc-shaped heating elements coinciding at the connection point. The inner heating element 205 and the outer heating element 201 are 1mm thick and 8mm wide. The main heating elements 202, 203, and 204 are all 1mm thick and 5mm wide. The main heating element 203 consists of 16 sequentially tangent arcs, each with a radius of 30mm. The main heating elements 202 and 204 are composed of 8 large arcs and 8 small arcs sequentially tangent, with a large arc radius of 43mm and a small arc radius of 18mm.

[0013] The cleaned and dried sapphire epitaxial substrate is placed in the sample inlet chamber of the molecular beam epitaxy (MBE) equipment. After a 1-hour high-temperature pretreatment, the sapphire substrate is transferred to substrate pit 101 of substrate tray 105 in the growth chamber of the MBE equipment using a transfer robotic arm. Substrate tray 105 rotates at 30 rpm via a rotating shaft. The inner heating element 205, main heating element 202, main heating element 203, main heating element 204, and outer heating element 201 are heated by electricity. The infrared temperature detection device of the MBE cavity detects and controls the heater power to achieve a temperature of 1000℃.

[0014] The above embodiments mainly illustrate that the present application provides a vacuum sample stage heating device suitable for four 4-inch epitaxial wafers. Although only one structure of the present application is described, the present application can be implemented in many other structures without deviating from the main idea and scope. Therefore, it should be understood that the above embodiments are not limited to the present application, and any modifications, replacements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A temperature field self-compensated vacuum sample stage heating device, mainly comprising a sample stage tray part, a heater part, a ceramic support part, a double-layer reflection plate part, and a rotating shaft part; characterized in that The heater part comprises five parts, from inside to outside, they are inner ring heating sheet, main heating sheet one, main heating sheet two, main heating sheet three and outer ring heating sheet, the main heating sheet two is formed by connecting the arc-shaped heating sheets with the same diameter size in turn, the geometric tangent lines of the adjacent two arc-shaped heating sheets at the connecting points coincide, the main heating sheet one and the main heating sheet three are formed by connecting the arc-shaped heating sheets with two different diameters in turn according to the sequence of small arc and large arc, the geometric tangent lines of the adjacent two arc-shaped heating sheets at the connecting points coincide, the adjacent arcs of the main heating sheet one, the main heating sheet two and the main heating sheet three along the radial direction are concentric circles, the small arc radius of the main heating sheet one is the same as the small arc radius of the main heating sheet three, the large arc radius of the main heating sheet one is the same as the large arc radius of the main heating sheet three, the vertical normal distance of the arcs of the main heating sheet one and the main heating sheet two is equal to the vertical normal distance of the arcs of the main heating sheet two and the main heating sheet three, the distance range is 5mm-10mm, the thickness of the inner ring heating sheet, the main heating sheet one, the main heating sheet two, the main heating sheet three and the outer ring heating sheet is the same, the thickness range is 0.5mm-1.5mm, the width of the main heating sheet one, the main heating sheet two and the main heating sheet three is the same, the width range is 2mm-10mm, the width of the inner ring heating sheet and the outer ring heating sheet is the same, and the width of the inner ring heating sheet is 1.5-3 times of the width of the main heating sheet one, the heating power of the inner ring heating sheet and the outer ring heating sheet is controlled independently, the heating power of the main heating sheet one, the main heating sheet two and the main heating sheet three is coupled, the coupling relationship is that the heating power of the main heating sheet one is P1, the heating power of the main heating sheet two is P2, the heating power of the main heating sheet three is P3, then P1=a+bP2; P3=c+dP2, wherein the parameter values of a and c are determined by the structure and material parameters of the heater, and the parameter values of b and d are determined by the target temperature of the heater.

2. The temperature field self-compensated vacuum sample stage heating device according to claim 1, wherein, The heating sheet materials of the inner ring heating sheet, the main heating sheet one, the main heating sheet two, the main heating sheet three and the outer ring heating sheet include tungsten, rhenium, tungsten alloy, graphite or their combinations, and the ceramic support material includes boron nitride or aluminum oxide.

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