JP2012199397A - Substrate cooling method and vacuum processing apparatus - Google Patents

Abstract

A cooling method and a vacuum processing apparatus are provided for cooling a heated substrate more uniformly and rapidly.
A substrate cooling method according to an embodiment includes a step of transporting a substrate heated in a processing chamber capable of maintaining a reduced pressure state from the processing chamber to a load lock chamber capable of maintaining a reduced pressure state, and the load lock chamber. Supporting the outer periphery of the substrate conveyed to a guide mechanism provided in the load lock chamber, and bringing the cooling body closer to the main surface of the substrate supported by the guide mechanism without contacting the substrate, Cooling the substrate until the temperature of the substrate reaches a temperature T ₂ lower than a temperature T ₁ immediately after being transferred into the load lock chamber.
[Selection] Figure 3

Description

  Embodiments described herein relate generally to a substrate cooling method and a vacuum processing apparatus.

  When manufacturing a semiconductor device or the like, a process for cooling the substrate is often provided. For example, a silicon carbide (SiC) substrate may be used as a semiconductor substrate of a power MOSFET element. Such a silicon carbide substrate may be subjected to a high temperature treatment in the process of forming the power MOSFET. For example, when forming a source / drain region of a MOSFET on a silicon carbide substrate, ion implantation is performed while the substrate is in a high temperature state (for example, about 500 ° C.).

  However, the silicon carbide substrate has a higher thermal conductivity than the silicon (Si) substrate. Such a semiconductor substrate having a high thermal conductivity is desirably cooled as uniformly as possible after the high temperature treatment. For example, after a silicon carbide substrate supported on a support base is processed at a high temperature and then transferred to another support base, the surface of the silicon carbide substrate that exceeds the allowable value depending on the shape of the other support base. There is a case where the cooling is rapidly performed with the internal temperature distribution. As a result, thermal stress is generated in the substrate, and chipping or cracking occurs in the substrate.

  A measure of radiation cooling while leaving the semiconductor substrate in a high temperature state in a vacuum state without transporting it to another support stand is also conceivable, but this measure takes time for cooling and increases the tact time.

JP 2005-267931 A

  The problem to be solved by the present invention is to provide a substrate cooling method and a vacuum processing apparatus for cooling a heated substrate more uniformly and rapidly.

In the substrate cooling method according to the embodiment, the substrate heated in the process chamber capable of maintaining the decompressed state is transported from the process chamber into the load lock chamber capable of maintaining the decompressed state, and the substrate is transported into the load lock chamber. The outer periphery of the substrate is supported by a guide mechanism provided in the load lock chamber, and the temperature of the substrate is set close to the main surface of the substrate supported by the guide mechanism without contacting a cooling body. Cooling the substrate until a temperature T ₂ lower than a temperature T ₁ immediately after being transferred into the load lock chamber.

It is a plane schematic diagram of the vacuum processing apparatus which concerns on embodiment. It is a mimetic diagram of a load lock room concerning an embodiment. It is a cross-sectional schematic diagram of the load lock chamber according to the embodiment. It is a flowchart figure of the cooling method of the board | substrate which concerns on embodiment. It is a cross-sectional schematic diagram of the load lock chamber for demonstrating the cooling method of the board | substrate which concerns on embodiment. It is a figure explaining the effect of an embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. In the following description, the same members are denoted by the same reference numerals, and the description of the members once described is omitted as appropriate. Before explaining the substrate cooling method of the embodiment, a vacuum processing apparatus for carrying out this method will be explained.

FIG. 1 is a schematic plan view of a vacuum processing apparatus according to an embodiment.
The vacuum processing apparatus 1 is, for example, a single wafer vacuum processing apparatus, and includes load lock chambers 10 and 11, a vacuum processing chamber (processing chamber) 20, and a substrate transfer chamber 30.

  Each of the load lock chambers 10 and 11 can maintain a reduced pressure state, and a substrate (for example, a semiconductor substrate) 90 can be carried in and out. The load lock chamber 10 can store the substrate 90 that has been vacuum processed in the vacuum processing chamber 20, and the load lock chamber 11 can store the substrate 90 before being vacuum processed in the vacuum processing chamber 20. It is. In the vacuum processing apparatus 1, the substrate 90 installed in the load lock chamber 11 is transferred to the vacuum processing chamber 20 through the substrate transfer chamber 30. Then, after the substrate 90 is vacuum processed in the vacuum processing chamber 20, the substrate 90 is returned to the load lock chamber 10 through the substrate transfer chamber 30.

  The vacuum processing chamber 20 can maintain a reduced pressure state, and can perform any one of vacuum processing such as ion implantation, sputtering, CVD (Chemical Vapor Deposition), and dry etching, for example. The vacuum processing chamber 20 includes a support base 21 that can support the substrate 90. The support base 21 can heat the substrate 90 to a high temperature (for example, 500 ° C.).

  The substrate transfer chamber 30 is interposed between the load lock chambers 10 and 11 and the vacuum processing chamber 20. A vacuum robot (robot) 31 is provided in the substrate transfer chamber 30. The vacuum robot 31 has a transfer arm 32 that can support the outer periphery of the substrate 90. The vacuum robot 31 transports the substrate 90 from the load lock chamber 11 to the vacuum processing chamber 20 or transports the substrate 90 from the vacuum processing chamber 20 to the load lock chamber 10.

  Further, the vacuum processing apparatus 1 includes stocker chambers 40 and 41 and a substrate mechanism 50. The substrate mechanism 50 is interposed between the stocker chambers 40 and 41 and the load lock chambers 10 and 11. Cassette cases 42 and 43 capable of accommodating a plurality of substrates 90 are installed in the stocker chambers 40 and 41, respectively. The substrate mechanism 50 is provided with a vacuum robot 51 that transports the substrate 90 from the stocker chamber 40 to the load lock chamber 11 and transports the substrate 90 from the load lock chamber 10 to the stocker chamber 41. The vacuum robot 51 has a transfer arm 52 that can support the back surface of the substrate 90.

Next, the load lock chamber 10 of the vacuum processing apparatus 1 will be described in detail.
FIG. 2 is a schematic plan view of the load lock chamber according to the embodiment.
FIG. 3 is a schematic cross-sectional view of the load lock chamber according to the embodiment. 3 is a schematic cross-sectional view at the position of α-β in FIG.

The load lock chamber 10 includes a lid 100 that is an upper load lock chamber, a vacuum vessel 101 that is a lower load lock chamber, a metal block 110 that is a cooling body, and a lifter 11 that is a drive unit.
In the load lock chamber 10, the lid 100 and the vacuum vessel 101 are fitted, and in this fitted state, the inside of the load lock chamber 10 is brought into a reduced pressure state by an exhaust means by a vacuum pump (not shown). be able to. When the interior of the load lock chamber 10 is in the atmospheric state, the lid 100 is separated from the vacuum vessel 101 and the interior of the load lock chamber 10 is opened to the atmosphere. When the load lock chamber 10 is in the atmospheric state, the substrate 90 can be transferred from the load lock chamber 10 to the stocker chamber 41 described above. The substrate transfer chamber 30 and the above-described vacuum container 101 are connected to each other via a vacuum valve (not shown).

  The load lock chamber 10 has a ring-shaped guide mechanism 102. The guide mechanism 102 supports the outer periphery of the substrate 90 transferred into the load lock chamber 10. For example, the guide mechanism 102 supports a region 90 a of 2 mm to 4 mm inward from the outer end of the substrate 90.

  The load lock chamber 10 includes a cooling body that can approach the main surface (for example, the back surface) of the substrate 90 supported by the guide mechanism 102. A metal block 110 is illustrated as an example of the cooling body.

  The metal block 110 includes a metal block portion 110a having a semicircular planar shape and a metal block portion 110b having a semicircular planar shape. The metal block 110 part a and the metal block part 110 b face each other across the groove 110 t.

  The main component of the metal block 110 is, for example, aluminum (Al), copper (Cu), iron (Fe), or an alloy containing at least two of these metals. The transfer arm 52 can be inserted into the groove 110t between the metal block part 110a and the metal block part 110b.

  For example, after the substrate 90 is placed on the metal block 110, the transfer arm 52 is inserted between the metal block portion 110a and the metal block portion 110b. The substrate 90 can be taken out of the load lock chamber 10 by the transfer arm 52 by lifting the substrate 90 by the transfer arm 52 and supporting the substrate 90 by the transfer arm 52.

  The metal block 110 is connected to a lifter 111 that is a drive unit, and can move up and down. The lifter 111 allows the main surface of the substrate 90 supported by the guide mechanism 102 and the metal block 110 to approach each other, and the temperature of the substrate 90 is lower than the temperature T1 immediately after being transferred into the load lock chamber 10. The substrate 90 can be cooled until the temperature T2 is reached. For example, the distance between the main surface of the substrate 90 and the main surface of the metal block 110 in a state where the substrate 90 is supported by the guide mechanism 102 is “D”. The main surface 110s of the metal block 110 and the main surface of the substrate 90 face each other, and the distance D becomes longer or shorter. The vertical movement of the metal block 110 is controlled by the control mechanism 112.

  The temperature of the substrate 90 detected by the plurality of temperature sensors 120 is input to the control mechanism 112. The metal block 110 can approach the main surface (for example, the back surface) of the substrate 90 supported by the guide mechanism 102. Depending on the temperature of the substrate 90, the distance D can be changed, or the speed at which the metal block 110 approaches the substrate 90 can be changed.

In the load lock chamber 10, the temperature T ₁ of the substrate 90 immediately after being transferred into the load lock chamber 10 is set to a temperature T ₂ lower than the temperature T ₁ by bringing the metal block 110 close to the substrate 90 without contacting the substrate 90. The substrate 90 can be cooled until A temperature control medium may be flowed through the metal block 110 as necessary. Thereby, even if the metal block 110 receives the heat from the outside, it is kept at a constant temperature.

  The load lock chamber 10 is provided with a temperature sensor 120 for monitoring the temperature of the substrate 90. The temperature sensor 120 is, for example, a thermal radiation type thermometer.

Note that each of the temperature T ₁ and the temperature T ₂ may be a single temperature at the center of the main surface of the substrate 90, and each of the temperature T ₁ and the temperature T ₂ is a temperature at a plurality of locations in the main surface of the substrate 90. It is good also as an average value of. The plurality of locations may be three points including the center of the main surface of the substrate 90 and two points on the outer periphery of the substrate 90 on a straight line passing through the center. Alternatively, the plurality of locations are the center of the main surface of the substrate 90, two points on the outer periphery of the substrate 90 on a straight line passing through this center, and the substrate 90 on another straight line passing through the center and orthogonal to the straight line. 5 points including 2 points on the outer periphery of In addition, about a some location, it is not limited to these numbers. An average value of the substrate temperatures measured at a plurality of locations is referred to as an in-plane average temperature.

  Next, a method for cooling the substrate 90 according to the embodiment will be described. In the embodiment, the substrate 90 subjected to the high temperature processing in the vacuum processing chamber 20 is cooled more uniformly and rapidly in the load lock chamber 10. The substrate 90 is a semiconductor substrate containing, for example, silicon carbide (SiC).

FIG. 4 is a flowchart of the substrate cooling method according to the embodiment.
FIG. 5 is a schematic cross-sectional view of the load lock chamber for explaining the substrate cooling method according to the embodiment.

  The substrate 90 heated to about 500 ° C. in the vacuum processing chamber 20 is transferred from the vacuum processing chamber 20 to the load lock chamber 10 via the substrate transfer chamber 30 (step S10).

  The substrate 90 is heated in advance to about 500 ° C. in the vacuum processing chamber 20 before being transferred into the load lock chamber 10. For example, when the vacuum processing chamber 20 is an ion implantation apparatus, when ion implantation is performed on a silicon carbide substrate, the ion implantation is performed at a high temperature of, for example, about 500 ° C. in order to avoid amorphization of the silicon carbide substrate. do. In the load lock chamber 10, when the temperature of the substrate 90 is increased, the temperature is slowly increased, for example, in a pulse shape so as not to apply a sudden thermal stress to the substrate 90. Thereafter, the substrate 90 is transferred from the vacuum processing chamber 20 to the load lock chamber 10 via the substrate transfer chamber 30.

  Subsequently, the outer periphery of the substrate 90 transferred into the load lock chamber 10 is supported by the guide mechanism 102 provided in the load lock chamber 10 (step S20).

  FIG. 5A shows a state where the substrate 90 is supported by the guide mechanism 102.

  The distance between the substrate 90 and the metal block 110 at this time is D1. Next, monitoring of the temperature of the substrate 90 is started (step S30). The temperature monitoring is performed by a plurality of temperature sensors 120, for example.

  Next, the metal block 110 is brought close to the main surface (for example, the back surface) of the substrate 90 supported by the guide mechanism 102 (step S40). The distance between the substrate 90 and the metal block 110 at this time is D2.

FIG. 5B shows a state in which the metal block 110 is closer to the main surface of the substrate 90 than in FIG. 5A (D2 <D1). The distance D between the metal block 110 and the substrate 90 is maintained at a predetermined distance, or the distance D is reduced by gradually bringing the metal block 110 closer to the substrate 90. As the metal block 110 approaches the substrate 90, the radiant heat emitted from the substrate 90 is efficiently absorbed by the metal block 110. Thereby, the board | substrate 90 can be cooled rapidly. Then, the substrate 90 is cooled until the temperature T ₁ (as an example, 350 ° C.) immediately after being transferred into the load lock chamber 10 to the temperature T ₂ (as an example, 200 ° C.) (step). S50).

In step S50, the metal block 110 is driven while the temperature sensor 120 detects the temperature of the substrate 90. In the stage from the temperature T ₁ to the temperature T ₂ , the metal block 110 is not brought into contact with the substrate 90.

For example, in step S50, a temperature sensor 120, while monitoring the temperature of the substrate 90, the cooling rate at the time of lowering the temperature of the substrate from the temperatures T ₁ to the temperature T _2, 10 (℃ / sec) was controlled to below Yes. If the cooling rate is greater than 10 (° C./second), the substrate 90 may be subjected to rapid thermal stress, and the substrate 90 may be cracked or the substrate 90 may be chipped. For example, when the substrate 90 is a substrate having a high thermal conductivity such as a SiC substrate, cracking and chipping are likely to occur. In particular, as the cooling start temperature (T ₁ ) is higher and the cooling rate is faster, a larger amount of heat release occurs in the substrate 90 during the cooling process. For this reason, rapid thermal stress is likely to be applied to the substrate 90. Therefore, as in the embodiment, the cooling rate is desirably 10 (° C./second) or less.

  In step S50, the substrate 90 is cooled so that the temperature distribution of the substrate 90 in which the cooling of the substrate 90 is in progress does not exceed the allowable value. As one of the measures for this purpose, the portion where the substrate 90 is in contact with another member (guide mechanism 102) is only the outer edge (region 90a) where the substrate 90 and the guide mechanism 102 are in contact.

Further, when the temperature T ₁ and the temperature T ₂ are the in-plane average temperatures of the substrate 90, the difference ΔT between the maximum temperature and the minimum temperature among the temperatures at a plurality of locations on the main surface of the substrate 90 is 20 The distance D is maintained at a predetermined distance so as to be equal to or lower than 0 ° C., or the metal block 110 is gradually brought closer to the substrate 90. When ΔT is 20 ° C., ΔT is the maximum allowable value.

  If the difference between the temperature and the minimum temperature is greater than 20 ° C., the substrate 90 may be subjected to rapid thermal stress, and the substrate 90 may be cracked or the substrate 90 may be chipped. For this reason, when the temperature of the substrate 90 is lowered from the temperature T1 to the temperature T2, the difference between the highest temperature and the lowest temperature among the temperatures at the plurality of locations is desirably 20 ° C. or less.

Next, after the substrate 90 becomes lower than the temperature T ₂ (for example, 200 ° C.), the substrate is brought into contact with the metal block 110 (step S60). This state is shown in FIG. At this stage, since the substrate 90 is sufficiently cooled, the substrate 90 is chipped and is not easily cracked.

  Thereafter, the inside of the load lock chamber 10 is in an atmospheric state, and the substrate 90 can be taken out from the load lock chamber 10. In order to cool the substrate 90 more slowly, the volume of the load lock chamber 10 may be larger than the volume of the load lock chamber 11.

FIG. 6 is a diagram for explaining the effect of the embodiment.
The horizontal axis is time (seconds), and the vertical axis is the temperature of the substrate 90.

On the horizontal axis, a time X immediately after the substrate 90 is transferred from the vacuum processing chamber 20 into the load lock chamber 10 and a time Y after the substrate 90 is cooled by the metal block 110 are shown. Here, the substrate temperature T ₁ is 350 ° C. or more and 400 ° C. or less, and the substrate temperature T ₂ is 150 ° C. or more and 200 ° C. or less. In the drawing, examples of substrate temperatures of 350 ° C. and 200 ° C. are shown as examples. The embodiment is not limited to these values.

First, line A is an example in which the metal block 110 is not provided and the substrate 90 is cooled while being left in a vacuum state. In this case, the periphery of the substrate 90 is a vacuum. In such a situation, since the substrate 90 is cooled by the radiative cooling into the vacuum, the cooling time becomes long. Thus, the slope of the line A becomes gentle, the substrate 90 is carried into the load lock chamber 10, the tact time until the substrate temperature is T ₂ rises.

  On the other hand, line B is an example of temperature change when placed on the metal block 110 immediately after being transferred from the vacuum processing chamber 20 into the load lock chamber 10. In this case, although the substrate 90 is rapidly cooled, the substrate 90 is cooled in a state where the temperature distribution exceeds the allowable value. As a result, thermal stress may occur in the substrate 90 and the substrate 90 may be chipped or cracked.

  On the other hand, line C is an example of the embodiment. In this case, the substrate 90 is cooled more quickly than the line A, and is cooled so that the temperature distribution in the substrate surface becomes more uniform than the line B. Therefore, the substrate 90 is not cooled while having a temperature distribution exceeding the allowable value, and thermal stress is hardly generated in the substrate 90. As a result, the substrate 90 is less likely to be chipped or cracked. In the embodiment, the cooling rate of the substrate 90 can be changed by changing the speed at which the metal block 110 approaches the substrate 90. For example, if the speed at which the metal block 110 is brought closer to the substrate 90 is made slower, the line C becomes like the line C1, and if the speed at which the metal block 110 is brought closer to the board 90 is made faster, the line C becomes the line C2. It becomes like this. Therefore, in the embodiment, the degree of freedom of the cooling rate of the substrate 90 is increased.

  Thus, according to the substrate cooling method according to the embodiment, a semiconductor substrate in a high temperature state can be cooled more uniformly and rapidly. The substrate cooling method according to the embodiment is effective for cooling a semiconductor substrate (for example, a SiC substrate) having high thermal conductivity.

  The embodiment has been described above with reference to specific examples. However, the embodiments are not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the embodiments as long as they include the features of the embodiments. Each element included in each of the specific examples described above and their arrangement, material, condition, shape, size, and the like are not limited to those illustrated, and can be appropriately changed.

  In addition, each element included in each of the above-described embodiments can be combined as long as technically possible, and combinations thereof are also included in the scope of the embodiment as long as they include the features of the embodiment. In addition, in the category of the idea of the embodiment, those skilled in the art can conceive various changes and modifications, and it is understood that these changes and modifications also belong to the scope of the embodiment. . For example, a method for causing the metal block 110 to approach from the upper surface side of the substrate 90 is also included in the embodiment.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1 Vacuum processing apparatus 10, 11 Load lock chamber 20 Vacuum processing chamber (processing chamber)
DESCRIPTION OF SYMBOLS 21 Support stand 30 Substrate transfer chamber 31 Vacuum robot 32 Transfer arm 40, 41 Stocker chamber 42 Cassette case 50 Transfer mechanism 51 Vacuum robot 52 Transfer arm 90 Substrate 90a Area 100 Lid 101 Vacuum container 102 Guide mechanism 110 Metal block 110a, 110b Metal Block part 110s Main surface 110t Groove 111 Lifter (drive part)
112 Control mechanism 120 Temperature sensor

Claims (5)

Transporting a substrate heated in a processing chamber capable of maintaining a reduced pressure state from the processing chamber to a load lock chamber capable of maintaining a reduced pressure state;
Supporting an outer periphery of the substrate transported into the load lock chamber with a guide mechanism provided in the load lock chamber;
The cooling body is brought close to the main surface of the substrate supported by the guide mechanism without contacting the substrate, and the temperature of the substrate becomes a temperature T ₂ lower than the temperature T ₁ immediately after being transferred into the load lock chamber. Cooling the substrate to
A substrate cooling method comprising:   The substrate cooling method according to claim 1, wherein the substrate is cooled while the distance between the main surface of the substrate supported by the guide mechanism and the cooling body is reduced. The substrate cooling method according to claim 1, wherein the substrate is brought into contact with the cooling body after the temperature of the substrate becomes lower than the temperature T ₂ .   The said board | substrate contains a silicon carbide, The board | substrate cooling method as described in any one of Claims 1-3 characterized by the above-mentioned. A load lock chamber capable of maintaining a reduced pressure state and capable of loading and unloading substrates;
A processing chamber capable of maintaining a reduced pressure state and heating the substrate;
A substrate transfer chamber provided with a robot capable of transferring the substrate from the vacuum processing chamber to the load lock chamber;
With
The load lock chamber includes a guide mechanism that supports an outer periphery of the substrate conveyed into the load lock chamber;
A cooling body;
The main surface of the substrate supported by the guide mechanism and the cooling body are brought close to each other until the temperature of the substrate becomes a temperature T ₂ lower than the temperature T ₁ immediately after being transferred into the load lock chamber, A driving unit capable of cooling the substrate;
A vacuum processing apparatus comprising:

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