A high uniformity wafer heater for reducing wafer ion contamination

Abstract

A high uniformity wafer heater for reducing wafer ion contamination comprises a metal heater body and a metal fixing ring, wherein the metal heater body is provided with a disk, a mounting shaft, a temperature measuring thermocouple and a plurality of gas pipelines, wherein the disk of the metal heater body is embedded with a plurality of square armored heating tubes and graphite heat spreaders, and a ceramic heat spreader is provided on the top surface; a metal fixing ring is provided on the periphery of the disk body and the ceramic heat spreader; the disk body is provided with a surface gas spreader groove, an outer ring sealing surface, an inner ring sealing surface, a square heating tube installation groove and a graphite heat spreader installation groove; the outer shell of the square armored heating tube is provided with a square shape, and the inside is provided with a circular armored heating tube; the top surface of the ceramic heat spreader is evenly distributed with a number of small bosses for supporting wafers. The invention has a novel structure, stable process, greatly extends the service life, reduces pollution during the process, significantly improves production efficiency and reduces production costs.

Description

Technical Field

[0001] The invention relates to the field of semiconductor manufacturing equipment, and in particular to a high-uniformity CVD wafer heater capable of reducing wafer ion contamination. Background Art

[0002] Wafer heaters are key components in the production process of semiconductor manufacturing equipment. In the CVD process, the wafer is in close contact with the heater, and metal ions will contaminate the wafer due to friction, seriously affecting the process. In addition, the surface where the heater contacts the wafer is prone to adsorb substances in the process, causing contamination to subsequent process wafers and affecting thermal uniformity, resulting in a shortened heater working cycle, requiring regular maintenance, and requiring disassembly for cleaning, which seriously affects production efficiency. In high-temperature processes, traditional aluminum alloy heaters can no longer be used. Traditional high-temperature resistant stainless steel heaters have poor uniformity due to the small contact surface of the material and the circular heating tube. The temperature measuring thermocouple is integrated inside the heater, and the wafer temperature deviates greatly from the measured temperature, seriously affecting the pass rate of the CVD process. Summary of the invention

[0003] The purpose of the present invention is to solve the above technical problems and provide a high uniformity wafer heater which can reduce wafer ion contamination.

[0004] In order to achieve the above technical objectives and meet the above technical requirements, the technical solution adopted by the present invention is:

[0005] A high-uniformity wafer heater for reducing wafer ion contamination, comprising a metal heater body and a metal fixing ring, characterized in that: the metal heater body is provided with a disk body, a mounting shaft is provided at the bottom of the disk body, a temperature measuring thermocouple and a plurality of gas pipelines are provided in the mounting shaft, a plurality of square armored heating tubes and graphite heat-distributing plates are embedded in the disk body of the metal heater body, and a ceramic heat-distributing disk is provided on the top surface; a metal fixing ring is provided on the periphery of the disk body and the ceramic heat-distributing disk; a surface gas-distributing groove, an outer ring sealing surface, an inner ring sealing surface, a square heating tube mounting groove and a graphite heat-distributing plate mounting groove are provided on the disk body; the square armored heating tube is provided with an inner-zone square armored heating tube and an outer-zone square armored heating tube, the outer shell of the square armored heating tube is provided with a square shape, and the interior is provided with a circular armored heating tube, and a heat-conducting layer is provided between the outer shell of the heating tube and the circular armored heating tube; a plurality of small bosses supporting wafers are evenly distributed on the top surface of the ceramic heat-distributing disk, and a sealing surface is provided on the bottom surface.

[0006] Preferably, the graphite heat-distributing plate is provided with an inner graphite heat-distributing plate and an outer graphite heat-distributing plate.

[0007] Preferably, the outer periphery of the metal fixing ring is provided with a sandblasting layer.

[0008] Preferably, the metal heater body is formed by welding a disc, a mounting shaft, a temperature measuring thermocouple and a plurality of gas pipelines by autogenous welding or electron beam welding.

[0009] Preferably, the disc body is made of high temperature resistant stainless steel or an alloy of the same high temperature with a working temperature of 800-1150 degrees.

[0010] Preferably, the heat-conducting layer is made of metal with good heat conductivity or magnesium oxide powder with better high temperature resistance.

[0011] Preferably, the temperature measuring thermocouple is a temperature measuring thermocouple with an elastically retractable ceramic disk.

[0012] The invention has a novel structure and a stable process, greatly prolongs the service life, reduces pollution during the process, significantly improves production efficiency, and reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the structure of the present invention;

[0014] Figure 2 It is the AA cross-sectional view of the present invention;

[0015] Figure 3 This is a schematic diagram of the front view of the metal heater body in the present invention;

[0016] Figure 4 for Figure 3 BB cross-sectional view;

[0017] Figure 5 This is a schematic diagram of the front view of the square armored heating tube of the present invention;

[0018] Figure 6 for Figure 5 CC section view;

[0019] Figure 7 for Figure 6 A partial enlarged view of

[0020] Figure 8 It is a schematic diagram of the structure of the graphite heat distributing plate in the present invention;

[0021] Fig. 9 This is a schematic diagram of the structure of the ceramic uniform heating plate in the present invention;

[0022] Fig.10 It is the FF cross-sectional view in Picture 9;

[0023] In the figure: 1. Metal heater body; 1-1. Disk body; 1-2. Surface gas distribution groove; 1-3. Outer ring sealing surface; 1-4. Inner ring sealing surface; 1-5. Square heating tube installation groove; 1-6. Graphite heat distribution plate installation groove; 1-7. Temperature measuring thermocouple; 1-8. Gas pipeline; 1-9. Installation axis; 2. Square armored heating tube; 2-1. Inner area square armored heating tube; 2-2. Outer area square armored heating tube; 2-3. Square shell of heating tube; 2-4. Heat conducting layer; 2-5. Internal circular armored heating tube; 3. Graphite heat distribution plate; 3-1. Inner area graphite heat distribution plate; 3-3. Outer area graphite heat distribution plate; 4. Ceramic heat distribution plate; 4-1. Small boss for supporting wafer; 4-2. Sealing surface; 5. Metal fixing ring. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] In the figure: a high uniformity wafer heater for reducing wafer ion contamination, comprising a metal heater body 1, a metal fixing ring 5, characterized in that: the metal heater body 1 is provided with a disk body 1-1, a mounting shaft 1-9 is provided at the bottom of the disk body 1-1, a temperature measuring thermocouple 1-7 and a plurality of gas pipelines 1-8 are provided in the mounting shaft 1-9, a plurality of square armored heating tubes 2 and a graphite uniform heat plate 3 are embedded in the disk body 1-1 of the metal heater body 1, and a ceramic uniform heat plate 4 is provided on the top surface; the disk body 1-1 and the ceramic uniform heat plate 4 are provided with a metal fixing ring 5 on the periphery; the disk body 1-1 and the ceramic uniform heat plate 4 are provided with a metal fixing ring 5; 1 is provided with a surface gas-uniform groove 1-2, an outer ring sealing surface 1-3, an inner ring sealing surface 1-4, a square heating tube installation groove 1-5 and a graphite heat-uniform plate installation groove 1-6; the square armored heating tube 2 is provided with an inner area square armored heating tube 2-1 and an outer area square armored heating tube 2-2, the outer shell of the square armored heating tube is set as a square, the inside is set as a circular armored heating tube, and a heat-conducting layer 2-4 is set between the outer shell of the heating tube and the circular armored heating tube; the top surface of the ceramic heat-uniform plate 4 is evenly distributed with a number of small bosses 4-1 supporting wafers, and the bottom surface is provided with a sealing surface 4-2. The graphite heat-uniform plate 3 is provided with an inner area graphite heat-uniform plate 3-1 and an outer area graphite heat-uniform plate 3-3. The outer periphery of the metal fixing ring 5 is provided with a sandblasting layer. The metal heater body 1 is composed of a disk body 1-1, a mounting shaft 1-9, a temperature measuring thermocouple 1-7 and a plurality of gas pipelines 1-8, which are welded together by self-melting welding and electron beam welding. The disk body 1-1 is made of high-temperature resistant stainless steel or alloys with the same high temperature, which has a working temperature of 800-1150 degrees. The heat-conducting layer 2-4 is made of metal with good thermal conductivity or magnesium oxide powder with higher temperature resistance. The temperature measuring thermocouple is a ceramic disk temperature measuring thermocouple with elastic expansion.

[0026] In specific implementation, the square armored heating tube 2 has the following features: (a) The heating tube uses a double-layer sealed shell structure design, with a square outside and a round inside, which will not cause the ordinary single-layer shell to deform after heating and cause the heating tube to be damaged; (b) The double-layer sealed shell can be filled with metal with good thermal conductivity or more high-temperature resistant magnesium oxide powder according to different temperature requirements; (c) Each heating tube is screened by temperature cycle detection to ensure good temperature distribution, prevent local overheating, and ensure the service life of the heating tube. The square armored heating tube is embedded in the square groove of the metal heater body, and vacuum brazing is used to achieve a close combination of the heating tube and the heating substrate: (a) The square armored heating tube and the square groove on the heater body are tightly matched, ensuring that the heating tube fits tightly into the groove after installation and maintains a good heat dissipation state; (b) Using vacuum brazing, the heating tube is pressed tightly in the groove to achieve simultaneous heat dissipation on all four sides, avoiding the problem of short service life caused by poor heat dissipation due to the inability of traditional round heating tubes to be in close contact with the groove. The heating plate 1-1 and the graphite heat spreader 3 are made of high-temperature resistant stainless steel or equivalent high-temperature alloy materials with an operating temperature of 800-1150 degrees, but their thermal conductivity is poor. Therefore, a graphite foil heat spreader with excellent thermal conductivity in the vertical direction is filled near the surface close to the wafer during operation, and is pressed with a special tooling, and the parts are vacuum brazed and sealed to ensure that the graphite heat spreader is in close contact with the upper and lower surfaces to ensure good thermal conductivity; the graphite foil heat spreader is divided into two or three pieces according to the number of square armored heating tubes to reduce the interference of temperature changes when the square armored heating tubes are working, and improve the temperature distribution uniformity of the heating plate. The heating plate is provided with a uniform gas groove and a sealing surface. The uniform gas groove uniformizes the temperature generated by the heating tube through gas to further improve the temperature uniformity; the sealing surface is used to contact the ceramic surface to ensure sealing. Ceramic heat spreader 4, a ceramic heat spreader with a small boss for supporting the wafer is also installed on the top surface of the heating plate. The small boss on the surface of the ceramic heat spreader to support the wafer can reduce the contact between the wafer and the heater and reduce wear; the square armored heating tube and the temperature control thermocouple are far away from the ceramic heat spreader, and the temperature of the ceramic heat spreader cannot be fed back in real time, which causes trouble to process control. A temperature measuring hole is processed in the center of the ceramic heat spreader, and the temperature measuring thermocouple is in close contact with the temperature measuring hole, which can accurately measure the process temperature. Metal fixing ring, the metal fixing ring presses the ceramic heat spreader to prevent air leakage; the outer surface of the metal fixing ring is sandblasted to increase the roughness and has the function of absorbing pollutants.

[0027] Working principle: The present invention uses a double-layer square armored heating tube and a square heating tube installation groove in close contact. Two or three armored heating tubes with separate temperature control generate heat and conduct the heat to the surface through a graphite heat spreader. The heat is evenly conducted to the ceramic heat spreader through the gas spreader groove, thereby heating the wafer. The temperature of the plate is measured in real time by a temperature measuring thermocouple in contact with the ceramic heat spreader to ensure process stability. At the same time, the ceramic heat spreader and the metal fixing ring protect the internal heater, and pollutants will be adsorbed by the sandblasting layer on the metal fixing ring.

[0028] The present invention is an assembled structural part. By using inner and outer square armored heating tubes to be embedded in tightly fitting square grooves of a high-temperature resistant stainless steel plate, a vacuum brazing process is used, and a graphite foil heat spreader is welded inside to improve the temperature uniformity of the metal heater. A ceramic heat spreader is installed on the heater. A thermocouple temperature measuring hole is opened on the ceramic heat spreader at a position very close to the wafer. The temperature of the wafer can be well controlled during the process to ensure process stability. At the same time, the ceramic heat spreader has good wear resistance, less pollution during the process, and greatly increased continuous working time, which can significantly improve production efficiency. At the same time, the price is lower than that of the integral ceramic heater.

[0029] The above embodiments of the present invention are merely examples to clearly illustrate the present invention, but are not intended to limit the protection scope of the present invention. All equivalent technical solutions also belong to the scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. A high uniformity wafer heater for reducing wafer ion contamination, comprising a metal heater body (1) and a metal fixing ring (5), characterized in that: The metal heater body (1) is provided with a disk body (1-1), a mounting shaft (1-9) is provided at the bottom of the disk body (1-1), a temperature measuring thermocouple (1-7) and a plurality of gas pipelines (1-8) are provided in the mounting shaft (1-9), a plurality of square armored heating tubes (2) and graphite uniform heat plates (3) are embedded in the disk body (1-1) of the metal heater body (1), and a ceramic uniform heat plate (4) is provided on the top surface; a metal fixing ring (5) is provided on the periphery of the disk body (1-1) and the ceramic uniform heat plate (4); a surface uniform gas groove (1-2), an outer ring sealing surface (1-3), an inner ring sealing surface (1-4), a square heating tube mounting groove (15) and a graphite uniform heat plate mounting groove (1-6) are provided on the disk body (1-1); the square armored heating tube (15) and the graphite uniform heat plate (1-6) are installed in the mounting shaft (1-9 ... The heat pipe (2) is provided with an inner square armored heating pipe (2-1) and an outer square armored heating pipe (2-2); the outer shell of the square armored heating pipe is arranged in a square shape, and the inside is arranged in a circular armored heating pipe; a heat conducting layer (2-4) is arranged between the outer shell of the heating pipe and the circular armored heating pipe; the top surface of the ceramic uniform heat plate (4) is evenly distributed with a number of small bosses (4-1) supporting wafers, and the bottom surface is provided with a sealing surface (4-2); the graphite uniform heat plate (3) is provided with an inner graphite uniform heat plate (3-1) and an outer graphite uniform heat plate (3-3); the heat conducting layer (2-4) is made of a metal with good thermal conductivity or magnesium oxide powder with better high temperature resistance; the heat conducting layer (2-4) is made of a metal with good thermal conductivity or magnesium oxide powder with better high temperature resistance.

2. A high uniformity wafer heater for reducing wafer ion contamination according to claim 1, characterized in that: The outer periphery of the metal fixing ring (5) is provided with a sandblasting layer.

3. The high uniformity wafer heater for reducing wafer ion contamination according to claim 1, characterized in that: The metal heater body (1) is formed by welding a disc (1-1), a mounting shaft (1-9), a temperature measuring thermocouple (1-7) and a plurality of gas pipelines (1-8) by means of autogenous welding or electron beam welding.

4. A high uniformity wafer heater for reducing wafer ion contamination according to claim 1 or 3, characterized in that: The disc body (1-1) is made of high-temperature resistant stainless steel or an alloy with the same high temperature, with a working temperature of 800-1150 degrees.

5. The high uniformity wafer heater for reducing wafer ion contamination according to claim 1, characterized in that: The temperature measuring thermocouple is a temperature measuring thermocouple with an elastically retractable ceramic disk.

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