JP2002198297A - Wafer heating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of taking a long time to stabilize the temperature of a soaking plate while cooling requires an extended time if a heat capacity on a semiconductor manufacturing equipment side is large when the soaking plate is fitted to the semiconductor manufacturing equipment. SOLUTION: A wafer heating device is provided where one main surface of the soaking plate of ceramics acts as a wafer placing surface, and a heating resistor is provided on the other main surface or inside while a feeding part electrically connected to the heating resistor is provided to the other main surface. Here, at least three gas jetting ports for cooling the soaking plate are provided in a concentric range whose diameter is 85% of the soaking plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer heating apparatus mainly used for heating a wafer, for example, forming a thin film on a wafer such as a semiconductor wafer, a liquid crystal device or a circuit board, or forming a wafer on the wafer. The present invention relates to a wafer heating apparatus suitable for forming a resist film by drying and baking a resist solution applied thereon.

[0002]

2. Description of the Related Art For example, in a semiconductor thin film forming process, an etching process, a resist film baking process, etc. in a manufacturing process of a semiconductor manufacturing apparatus, a semiconductor wafer (hereinafter abbreviated as "wafer") is heated to heat a semiconductor wafer. The device is used.

A conventional semiconductor manufacturing apparatus uses a batch-type apparatus for forming a plurality of wafers at a time. However, as the size of a wafer increases from 8 inches to 12 inches, the processing accuracy increases. In order to increase the quality, a technique called a single-wafer processing that processes one sheet at a time has been implemented in recent years. However, in the case of the single-wafer method, the number of processes per one process is reduced, so that the processing time of the wafer is required to be shortened. For this reason, it has been required for the wafer support member to shorten the heating time of the wafer, speed up the suction and desorption of the wafer, and improve the heating temperature accuracy.

In forming a resist film on a semiconductor wafer, one main surface of a heat equalizing plate 32 made of various metals such as an aluminum alloy or stainless steel as shown in FIG. A wafer heating device 31 is used in which a plurality of sheathed heaters 35 are brought into contact with the other main surface as the mounting surface 33 and held by a holding plate 34. Here, the temperature equalizing plate 32 is held by a support frame 37, and the temperature of the heat equalizing plate 32 is adjusted by causing a heating resistor composed of a sheathed heater 35 to generate heat by electric power supplied from a power supply unit 36. Has become.

The mounting surface 33 of the wafer heating device 31
After the wafer W coated with the resist solution is placed thereon, the heating resistor 35 composed of a sheathed heater is heated to heat the wafer W on the mounting surface 33 via the heat equalizing plate 32, and the resist solution is heated. Is dried and baked to form a resist film on the wafer W.

On the other hand, various methods have been proposed to increase the processing speed so that the soaking plate 32 can be rapidly heated, and at the same time, to take measures for cooling the wafer W faster.

For example, a heating device disclosed in Japanese Patent Application Laid-Open No. 2-196416 includes a plate heater for heating a wafer W and a supply device for supplying clean air, and an exhaust device for exhausting clean air used for cooling. Using a vent for allowing gas to flow inside each member, a shutter member for changing the flow path of clean air, and an elevating device (not shown) that can cool the wafer W while holding it on a plate heater, A method is introduced in which the wafer is cooled directly by passing clean air in the holding state.

Further, as shown in FIG.
The heating device 41 of Japanese Patent No. 299281 discloses a hot plate 45 for heating the wafer W and a hot plate 55 for heating the wafer W.
And a casing U having a substantially U-shape fixed by fixing screws 42. A space S1 is provided between the hot plate 45 and the casing 43 so as to allow a fluid to flow therethrough.

The casing 43 has a fluid supply port 44
And a fluid discharge port 46, respectively, for supplying air as a cooling fluid sent from a gas pressure pump (not shown) to the fluid supply port 44 with the hot plate 45.
After the heat is deprived of the hot plate 45, the hot plate 45 is forcibly cooled by flowing through the casing which has become a substantially closed space and discharging the fluid from the fluid discharge port 46.

[0010]

In order to process the workable resin film formed on the wafer surface repeatedly and in a short time, the cooling is performed while controlling the temperature distribution in the plane of the heat equalizing plate 2. It is necessary to. However, in the conventional heating device shown in FIG. 6, the cooling gas flow cannot be adjusted, so that the temperature variation during cooling may cause a new wafer to be placed on the soaking plate 2 and dried. As a result, there is a problem that the temperature distribution on the surface of the wafer W becomes large and uniform drying cannot be performed.

In particular, if there is only one gas injection port, there is a difference in cooling rate between the part where the gas is blown and the other part, resulting in a temperature distribution. This temperature distribution is eliminated and the uniform heat is improved. For this purpose, there is a problem that a certain time is required.

Further, if the gas flow rate is too high in order to increase the cooling rate, there is a problem that the heat generating resistor formed on the surface of the heat equalizing plate is deteriorated and durability is reduced.

Further, when a plurality of gas injection ports are provided,
When the outer peripheral part of the heat equalizing plate is cooled, the outer peripheral part cools faster than the heated central part, and the outer peripheral part contracts faster, so tensile stress occurs in the outer peripheral part and cracks are likely to occur in the heat equalizing plate There was a problem of becoming.

[0014]

Means for Solving the Problems As a result of diligent studies on the above-mentioned problems, the present inventors have found that one main surface of a soaking plate made of ceramics is used as a wafer mounting surface, and the other main surface or inside is provided. In a wafer heating apparatus having a heating resistor and having a power supply portion electrically connected to the heating resistor on the other main surface, a gas injection port for cooling the heat equalizing plate is provided. The above problem was solved by providing at least three or more of the heat equalizing plates in a range within a concentric circle having a diameter of 85%.

[0015] Further, a difference in cooling speed may be caused by disposing the gas injection ports on at least one substantially concentric circle at substantially equal intervals within a range of 85% or less of the outer diameter of the heat equalizing plate. In addition, uniform heating can be performed in a short time even when heating after placing a new wafer.

Further, by providing a plurality of gas supply paths for supplying a cooling gas to the gas injection port,
The cooling gas is uniformly supplied without pressure loss in the passage, and can be cooled uniformly and in a short time.

Further, by forming a coating layer having a thickness of 40 to 400 μm on the surface of the heat generating resistor formed on the other main surface, the gas injected from the gas injection port can be used for the other main surface. It is possible to provide a highly reliable wafer heating device that does not damage the formed heating resistor.

Further, the diameter of the gas injection port is 0.5 to
By setting the thickness to 3.0 mm, the cooling gas uniformly supplied from the plurality of fluid supply paths can be jetted at a uniform flow rate, and stable cooling performance can be obtained.

When the distance between the gas injection port and the heat equalizing plate is set to 0.8 to 8.0 mm, the heat equalizing plate is heated to stabilize the temperature. It is possible to stabilize in a short time with very little heat radiation from the gas injection port of the wafer, and also to improve the replacement speed of the gas on the surface of the soaking plate during cooling. can do.

Further, the gas injection port has a heat capacity of 0.15.
By making the metal or ceramic below cal / ° C,
When the temperature equalizing plate is heated to stabilize the temperature in the same manner as described above, the heat radiation from the gas injection port to the temperature equalizing plate can be stabilized in a short time, and the gas injection port can be stabilized even during cooling. Keeps the heat, the cooling gas can be cooled at a temperature suitable for cooling without warming, and the wafer heating apparatus can be cooled in a short time.

[0021]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view showing an example of a wafer heating apparatus 1 according to the present invention, in which one main surface of a heat equalizing plate 2 made of ceramics containing silicon carbide or aluminum nitride as a main component is placed on a wafer W. A heating resistor 5 is formed on the mounting surface 3 and an insulating layer 4 made of glass or resin is formed on the other main surface.

As the pattern shape of the heating resistor 5, the mounting surface 3 can be uniformly heated, such as a substantially concentric or spiral-shaped one having an arc-shaped electrode portion and a linear electrode portion. Any pattern shape is acceptable. In order to improve heat uniformity, the heating resistor 5 can be divided into a plurality of patterns.

The heating resistor 5 includes gold, silver, palladium,
A power supply unit 6 made of a material such as platinum is formed.
The conductive terminal 11 is pressed by an elastic body (not shown) and brought into contact with the conductive terminal 11 to ensure conduction.

Further, a bolt 16 is passed through the outer circumference of the heat equalizing plate 2 and the support 7, and a heat insulating portion 17 is interposed so that the heat equalizing plate 2 does not directly contact the support 7. The nut 20 is screwed on with the body 18 and the washer 19 interposed therebetween, thereby being elastically fixed. Thereby, the heat equalizing plate 2
When the temperature of the support fluctuates, even if the support 7 is deformed, it is absorbed by the elastic body 19, thereby suppressing the warping of the heat equalizing plate 2 and causing the warping of the heat equalizing plate 2 on the wafer surface. It is possible to prevent the occurrence of temperature fluctuations.

The metal support 7 has a side wall 9 and a multilayer structure 10, and the heat equalizing plate 2 is installed so as to cover an upper portion facing the multilayer structure 10. The multilayer structure 10 is provided with an opening 14 for discharging a cooling gas, and a conduction terminal 7 for conducting to a power supply 6 for supplying power to the heating resistor 5 of the heat equalizing plate 2. A gas injection port 12 for cooling the soaking plate 2 and a thermocouple 13 for measuring the temperature of the soaking plate 2 are provided.

Further, the multilayer structure 10 is composed of a plurality of layers, and the uppermost layer of the multilayer structure 10 is desirably installed at a distance of 5 to 15 mm from the heat equalizing plate 2. This is because the radiant heat between the heat equalizing plate 2 and the multilayer structure portion 10 facilitates the heat equalization, and at the same time, has a heat insulating effect with the other layers, so that the time until the heat equalization is shortened.

In the present invention, it is preferable that at least three or more gas injection ports 12 for cooling the heat equalizing plate 2 are provided within a concentric circle having a diameter of 85% of the heat equalizing plate 2. .

The position of the gas injection port 12 is
% Of the concentric circle having a diameter of 0.5% is that if the heat equalizing plate 2 is cooled by gas blowing on the outer side, the outer peripheral portion is first cooled and contracted with respect to the heated central portion. This is because a tensile stress is applied to the outer peripheral portion, whereby the heat equalizing plate 2 becomes fatigued and cracks occur during use.

Further, the gas injection port 12 is set to 85% of the heat equalizing plate 2.
The reason for providing at least three or more in a concentric circle having a diameter of for example is that, for example, in the case of one gas injection port 12, only the central part is cooled and the whole cannot be uniformly cooled. In addition, in the case of two, the line direction connecting the gas injection ports 12 has a cooling effect, but cooling in the direction perpendicular to this line direction is delayed, and the whole cannot be uniformly cooled.

If the temperature variation of the heat equalizing plate 2 at the time of cooling is large, the next time the wafer is placed on the heat equalizing plate 2 and heated, the effect remains, and the temperature distribution is not easily uniform. Occurs.

On the other hand, if at least three or more pieces are provided within a concentric circle having a diameter of 85% of the heat equalizing plate 2, good heat stress and good temperature uniformity can be obtained. Cooling can be performed.

The gas injection ports 12 are preferably arranged at substantially equal intervals on at least one substantially concentric circle. With such an arrangement, it is advantageous to cool the whole uniformly.

FIG. 4A is a plan view showing a case where three gas injection ports 12 are provided within a concentric circle having a diameter of 85% of the heat equalizing plate 2. FIG. 4B is a plan view showing a case where fifteen gas injection ports 12 are installed within a concentric circle having a diameter of 85% of the heat equalizing plate 2. In the installation state of FIG. 4A, the gas injection ports 12 are installed at substantially equal intervals on one substantially concentric circle. In the installation state of FIG. 4B, the gas injection ports (outer) 12a, the gas injection ports (middle) 12b, and the gas injection ports (inner) 12c are all disposed at substantially equal intervals on substantially concentric circles. It is preferable that the gas injection ports 12 are designed so that they can be installed at equal intervals in an arrangement that does not hinder the lift pin holes 8a and the openings 14.

Further, as shown in FIG. 1, the gas supply path 15 for supplying the cooling gas to the gas injection port 12 is desirably a plurality of paths. When all the gas injection ports 12 are connected in series by a single path, the gas injection amount is reduced due to a difference in distance to each gas injection port 12, a decrease in flow rate due to a pressure loss in the path due to a pipe diameter, meandering, and the like. Although a variation occurs, for example, the connection path to the gas injection port 12 is
By providing a plurality of paths such as half or the same number of two, variations in the gas injection amount can be suppressed and uniform cooling can be achieved.

Preferably, a coating layer having a thickness of 40 to 400 μm is formed on the surface of the heating resistor 5 formed on the other main surface. To accelerate the cooling of the soaking plate 2,
A large amount of gas of 1 to 100 × 10 ⁻³ m ³ / min is injected from the small gas injection port 12. For this reason, the heating resistor 5 is
After the heating, it is cooled directly by a large amount of air, so that it receives a large thermal shock and, in some cases, the glass in the heating resistor 5 is peeled off by the gas flow to shorten the life of the heating resistor 5. is there. Therefore, by forming a coating layer having a thickness of 40 to 400 μm on the surface of the heating resistor 5, the cooling gas is not directly injected to the heating resistor 5, so that the life of the heating resistor 5 can be extended.

Specifically, when the cooling gas injected from the gas injection port 12 is continuously applied for a long period of time, the conductive particles in the heating resistor 5 are dropped by the cooling gas. The film thickness of the heating resistor 5 gradually decreases, and the resistance value of the heating resistor 5 gradually increases, eventually leading to disconnection. In order to prevent such a problem, the heating resistor 5 is formed so as to cover the heating resistor 5.
The thickness of the heating resistor 5 is preferably set to 40 μm or more because the heating resistor 5 may be partially exposed due to the inability to absorb the irregularities. If the coat layer is extremely thick,
Since there is a difference in the coefficient of thermal expansion from the material, the thicker the thickness, the more the heat equalizing plate 2 is deformed. Therefore, the thickness is preferably 400 μm or less. In particular, when the thickness is 50 to 150 μm, the layer sufficiently plays a role of a protective layer, and the amount of deformation is small, so that there is little problem in production.

The diameter of the gas injection port 12 is 0.5
It is preferable to set it to 3.0 mm. If it is less than 0.5 mm, it is necessary to increase the gas pressure in order to increase the flow rate of the gas, and this tends to deteriorate the gas flow path and the connection part. It is not preferable because it is necessary to change the structure or the like. Further, if the diameter of the gas injection port 12 exceeds 3 mm, the flow velocity of the gas becomes small, and the cooling efficiency becomes low, which is not preferable.

Further, the distance between the gas injection port 12 and the heat equalizing plate 2 is preferably set to 0.8 to 8.0 mm. If the distance is less than 0.8 mm, the gas injection port 12
Is not preferable because the temperature rise of the heat equalizing plate 2 in the vicinity thereof becomes slow due to the influence of the heat capacity, or the temperature of the gas injected from the heated gas injection port 12 becomes high and the cooling efficiency decreases. On the other hand, if the distance exceeds 8.0 mm, the flow velocity of the gas reaching the surface of the heat equalizing plate 2 becomes slow due to the spread of the gas flow, and as a result, the cooling speed of the heat equalizing plate 2 becomes low, which is not preferable. .

The gas injection port 12 has a heat capacity of 0.1.
It is preferable to use a metal or ceramic having a caloric value of 5 cal / g · ° C. or less. If the heat capacity of the gas injection port 12 exceeds 0.15 cal / g · ° C., it is not preferable because the heat capacity of the gas injection port 12 affects the temperature rise and fall of the heat equalizing plate 2.

Specifically, stainless steel (Fe—Ni—C
r alloy), nickel (Ni) or other oxidation-resistant metal, or a metal material obtained by subjecting general steel (Fe) or titanium (Ti) to nickel plating or gold plating over nickel plating and subjected to oxidation resistance, Ceramics such as zirconia (ZrO ₂ ) are preferably used.

Further, the gas injection port 12 made of the above-mentioned metal or ceramic material has an advantage in terms of heat capacity, but also has a thermal characteristic of stainless steel (Fe-Fe).
(Ni-Cr alloy), nickel (Ni), or other oxidation-resistant metal, or a metal material obtained by subjecting general steel (Fe) or titanium (Ti) to nickel plating or a metal material obtained by superimposing gold plating on nickel plating and subjecting it to oxidation resistance. Is preferred. Gas injection port 12
This is because the heater is used immediately near the heating resistor 5 and may be oxidized by heat.

As the type of the cooling gas, it is advantageous for cooling to use a gas having a large constant-pressure heat capacity, but from the viewpoint of safety, it is preferable to use dry air or carbon dioxide gas. Further, the gas flow rate from each gas injection port 12 is preferably set to 1 to 100 × 10 ⁻³ m ³ / min.

In order to discharge the supplied gas to the outside, the multilayer structure 10 of the support 7 is provided with an opening 14 having an area of 5 to 70% of the area thereof. If the area of the opening 14 is less than 5%, the gas injected from the gas injection port 12 and the gas to be discharged are mixed in the volume of the support 7, and the cooling efficiency is reduced. When the area of the opening 14 exceeds 70%, the conductive terminal 1
1 and the space for holding the fluid ejection port 12 are insufficient and the strength is insufficient, the pressing force of the conductive terminal 11 against the electrode pad 6 is not stable, and the durability at the time of intermittent use is deteriorated.

As described above, by providing the openings in the multilayer structure portion 14, the cooling gas injected from the gas injection ports 12 receives the heat of the surface of the heat equalizing plate 2 during cooling, and
1 is discharged out of the layer sequentially from the opening without staying in the inside, and the surface of the heat equalizing plate 2 can be efficiently cooled by the new cooling gas injected from the gas injection port 12, so that the cooling time can be shortened.

The shape of the gas injection port 12 is shown in FIG.
It has a shape as shown in (a) and (b). FIG. 3 (a)
FIG. 3 is a cross-sectional view when cooling gas is introduced into the gas introduction portion 23 of the gas injection port 12 from two directions. This gas injection port 12
Is passed through the gas introduction part 23 through the multilayer structure part 10 and is fixed to the multilayer structure part 10 using a hexagon nut 24 using a threaded portion provided on the surface of the gas introduction part 23. The gas supply path 15 is connected to the gas injection port 12 by a clamp ring 25. The cooling gas flows through the connected gas supply paths 15 on both sides, and is injected from the bore 21 toward the soaking plate 2.

FIG. 3B is a cross-sectional view when the cooling gas is introduced into the gas inlet 23 of the gas injection port 12 through a single path. 3A, the cooling gas is fixed to the multilayer structure portion 10 and the cooling gas is jetted toward the heat equalizing plate 2. As shown in FIG. Note that the shape of the gas injection port is not limited to the illustrated shape.

Further, the work of placing the wafer W on the mounting surface 3 or lifting it from the mounting surface 3 is performed by the lift pins 8 installed in the support 7 so as to be able to move up and down. Then, the wafer W is placed on the mounting surface 3 by the wafer support pins 17.
It is held in a state of being floated from above, so as to prevent a temperature variation due to one-side contact or the like.

To heat the wafer W by the wafer heating device 1, the wafer W carried above the mounting surface 3 by the transfer arm (not shown) is supported by the lift pins 8, and then the lift pins 8 Is lowered to place the wafer W on the mounting surface 3.

Next, the power supply 6 is energized to cause the heat generating resistor 5 to generate heat, and the wafer W on the mounting surface 3 is heated via the insulating layer 4 and the soaking plate 2. According to this, since the support 11 is provided with the multilayer structure 14, the multilayer structure 14 adjacent to the heat equalizing plate 2 can be used as a heat radiation plate of the heat equalizing plate 2. It can be soaked in a short time.

Furthermore, since the heat equalizing plate 2 is formed of a silicon carbide sintered body or an aluminum nitride sintered body, deformation is small even when heat is applied, and the plate thickness can be reduced. The heating time before heating to a temperature and the cooling time until cooling from a predetermined processing temperature to around room temperature can be shortened, and productivity can be improved, and the thermal conductivity of 50 W / m · K or more From having
Even with a small thickness, the Joule heat of the heating resistor 5 can be quickly transmitted, and the temperature variation of the mounting surface 3 can be extremely reduced.

Further, as another embodiment, as shown in FIG. 2, a heater in which the heating resistor 5 is incorporated in the heat equalizing plate 2 may be used.

The thickness of the heat equalizing plate 2 is preferably 2 to 7 mm. If the thickness of the heat equalizing plate 2 is less than 2 mm, the strength of the heat equalizing plate 2 is weakened, and when heating by the heat generated by the heat generating resistor 5, when the cooling fluid is sprayed from the fluid ejection port 12,
It cannot withstand the thermal stress during cooling, and cracks occur in the heat equalizing plate 2. On the other hand, if the thickness of the heat equalizing plate 2 exceeds 7 mm, the heat capacity of the heat equalizing plate 2 increases, so that the time until the temperature during heating and cooling stabilizes becomes long, which is not preferable.

As described above, when the heat capacity of the heat equalizing plate 2 is reduced, the temperature distribution of the heat equalizing plate 2 is deteriorated due to the heat drawn from the support 7. Therefore, the support 7 has a structure in which the heat equalizing plate 2 is held at the outer peripheral portion.

As to the method of supplying power to the heating resistor 5, the conductive terminal 11 provided on the support 7 is pressed by a spring (not shown) against the power supply section 6 formed on the surface of the heat equalizing plate 2. To secure the connection and supply power. This is 2
This is because if a terminal portion made of metal is buried and formed in the heat equalizing plate 2 having a thickness of about 7 mm, the heat capacity of the terminal portion deteriorates the heat uniformity. Therefore, as in the present invention, the conductive terminals 11 are pressed by a spring to secure the electrical connection, thereby alleviating the thermal stress caused by the temperature difference between the heat equalizing plate 2 and the support 7 thereof, and achieving high reliability. Can maintain electrical continuity. Furthermore, an elastic conductor may be inserted as an intermediate layer in order to prevent the contacts from becoming point contacts. This intermediate layer is effective simply by inserting a foil-like sheet. The diameter of the conduction terminal 7 on the side of the power supply unit 6 is preferably 1.5 to 4 mm.

The temperature of the soaking plate 2 is measured by a thermocouple 13 whose tip is embedded in the soaking plate 2. As the thermocouple 13, from the viewpoint of its responsiveness and workability of holding,
It is preferable to use a sheath-type thermocouple 13 having an outer diameter of 1.0 mm or less. The tip of this thermocouple 13 is
It is preferable to press and fix the inner wall surface of the cylindrical metal body provided therein with a spring material in order to improve the reliability of temperature measurement.

Further, when used as a wafer heating apparatus 1 for forming a resist film, if the main component of the heat equalizing plate 2 is silicon carbide, it does not react with moisture in the atmosphere and generate gas. Even if it is used for attaching a resist film on the wafer W, fine wiring can be formed at high density without adversely affecting the structure of the resist film. At this time, it is necessary to prevent the sintering aid from containing a nitride that may react with water to form ammonia or an amine.

The silicon carbide sintered body forming the heat equalizing plate 2 may be obtained by adding boron (B) and carbon (C) as sintering aids to silicon carbide as a main component, or adding alumina ( Al ₂ O ₃ ) A metal oxide such as yttria (Y ₂ O ₃ ) is added, mixed well, processed into a flat plate, and
It is obtained by firing at 0 to 2100 ° C. Silicon carbide may be any of those mainly composed of α-type and those mainly composed of β-type.

In addition, the aluminum nitride sintered body forming the heat equalizing plate 2 requires a rare earth element oxide such as Y ₂ O ₃ or Yb ₂ O ₃ as a sintering aid with respect to aluminum nitride as a main component. According to the above, an alkaline earth metal oxide such as CaO is added, mixed well, processed into a plate shape,
It is obtained by firing at 0 to 2100 ° C.

Further, the main surface of the heat equalizing plate 2 on the side opposite to the mounting surface 3 has a flatness of 20 μm or less and a surface roughness of the center line from the viewpoint of enhancing the adhesion to the insulating layer 4 made of glass or resin. It is preferable to polish to an average roughness (Ra) of 0.1 μm to 0.5 μm.

On the other hand, when a silicon carbide sintered body is used as the soaking plate 2, the insulating layer 4 for maintaining insulation between the soaking plate 2 having semiconductivity and the heating resistor 5 is made of glass or glass. It is possible to use a resin, and when using glass, if the thickness is less than 100 μm, the withstand voltage is less than 1.5 kV and insulation cannot be maintained, and if the thickness exceeds 400 μm,
Since the difference in thermal expansion between the silicon carbide-based sintered body and the aluminum nitride-based sintered body forming the heat equalizing plate 2 becomes too large, cracks occur, and the insulating layer 4 does not function. Therefore, when glass is used as the insulating layer 4, the thickness of the insulating layer 4 is preferably formed in the range of 100 to 400 μm, and more preferably in the range of 200 to 350 μm.

When the soaking plate 2 is formed of a sintered body containing aluminum nitride as a main component, an insulating layer made of glass is used to improve the adhesion of the heating resistor 5 to the soaking plate 2. 4 is formed. However, when sufficient glass is added to the heat generating resistor 5 and a sufficient adhesion strength can be obtained by this, it can be omitted.

The glass forming the insulating layer 4 may be crystalline or amorphous, and has a heat resistance of 200 ° C. or higher and a thermal expansion coefficient in a temperature range of 0 ° C. to 200 ° C. It is preferable to appropriately select and use a ceramic having a coefficient of thermal expansion in the range of -5 to + 5 × 10 ⁻⁷ / ° C. with respect to the thermal expansion coefficient of the ceramic constituting the plate 2. In other words, when a glass having a coefficient of thermal expansion outside the above range is used, the difference in thermal expansion between the ceramic forming the soaking plate 2 and the ceramic becomes too large.
This is because defects such as cracks and peeling easily occur during cooling after baking of the glass.

In addition, the insulating layer 4 made of glass was
As a means for coating on the top, an appropriate amount of the glass paste is dropped on the center of the heat equalizing plate 2 and spread by a spin coating method to apply uniformly, or a screen printing method, a dipping method, a spray coating method, or the like. Then, the glass paste may be baked at a temperature of 600 ° C. or more. When glass is used as the insulating layer 4, the heat equalizing plate 2 made of a silicon carbide sintered body or an aluminum nitride sintered body is previously heated to a temperature of about 850 to 1300 ° C., and the insulating layer 4 is applied. By oxidizing the surface, adhesion to the insulating layer 4 made of glass can be improved.

Further, as a material of the heating resistor 5 to be deposited on the insulating layer 4, gold (Au), silver (Ag), copper (C
u), a simple metal such as palladium (Pd) is directly applied by a vapor deposition method or a plating method, or the simple metal, rhenium oxide (Re ₂ O ₃ ), lanthanum manganate (La) is used.
A conductive metal oxide such as MnO ₃ ) or a paste obtained by dispersing the above metal material in a resin paste or a glass paste is prepared, printed in a predetermined pattern shape by a screen printing method or the like, and then baked. The materials may be joined by a matrix made of resin or glass. When glass is used as the matrix, either crystallized glass or amorphous glass may be used, but it is preferable to use crystallized glass in order to suppress a change in resistance due to thermal cycling.

However, when silver (Ag) or copper (Cu) is used as the material of the heating resistor 5, migration may occur. In such a case, the heating resistor 5 is used.
May be covered with a coat layer made of the same material as the insulating layer 4 to a thickness of about 40 to 400 μm.

In FIG. 1, the power supply 6 is connected to the heating resistor 5.
In (2), the conduction terminal 11 is pressed by a spring (not shown) to ensure conduction. The power supply section 6 may be formed by applying and curing a conductive adhesive on the terminal section of the heating resistor 5.

The heating resistor 5 has been connected to the heat equalizing plate 2 so far.
Although the wafer heating apparatus 1 of the type formed on the surface of the above has been described, the heating resistor 5 may be built in the heat equalizing plate 2.

Referring to FIG. 2 as an example, for example, when a heat equalizing plate 2 whose main component is made of aluminum nitride is used, first, the material of the heating resistor 5 is made of W Alternatively, WC is used. The heat equalizing plate 2 is formed into a disc shape after sufficiently mixing raw materials containing aluminum nitride as a main component and appropriately containing a sintering aid, and a paste made of W or WC is formed on the surface thereof in a pattern shape of the heating resistor 5. It can be obtained by printing, stacking another aluminum nitride molded body on top of the printed body, and then sintering it at a temperature of 1900 to 2100 ° C. in nitrogen gas.

The conduction from the heating resistor 5 can be achieved by forming a through hole in the aluminum nitride base material, embedding a paste made of W or WC, and firing the paste to draw out the electrode to the surface. good. When the heating temperature of the wafer W is high, the power supply unit 6 applies a paste containing a noble metal such as Au or Ag as a main component on the through-hole and bake it at 900 to 1000 ° C. Oxidation of the body 5 can be prevented.

[0071]

EXAMPLES Example 1 A plurality of disc-shaped soaking plates 2 having a thickness of 4 mm and an outer diameter of 230 mm were manufactured by grinding a silicon carbide sintered body having a thermal conductivity of 80 W / m · K. In order to apply the insulating layer 4 to one main surface of each heat equalizing plate 2, a glass paste prepared by kneading a binder composed of ethyl cellulose and an organic solvent terpineol into glass powder is printed by a screen printing method, After heating to 150 ° C. to dry the organic solvent, the organic solvent was degreased at 550 ° C. for 30 minutes.
By baking at a temperature of 900 ° C., an insulating layer 4 made of glass and having a thickness of 200 μm was obtained.

Next, in order to apply the heating resistor 5 on the insulating layer 4, a conductive paste prepared by kneading Au powder and Pd powder as conductive materials and a glass paste to which a binder having the same composition as described above was added was kneaded. Is printed in a predetermined pattern shape by a screen printing method, heated to 150 ° C. to dry the organic solvent, subjected to a degreasing treatment at 550 ° C. for 30 minutes, and then baked at a temperature of 700 to 900 ° C. Thereby, the heating resistor 5 having a thickness of 50 μm was formed. The heating resistor 5 has a center part and an outer part
Five divided patterns were used. Thereafter, the power supply unit 6 was fixed to the heating resistor 5 with a conductive adhesive, whereby the heat equalizing plate 2 was manufactured.

The support 7 is made of SU 2.5 mm thick.
Two multi-layered structural parts 10 made of S304 are prepared, and one of them is provided with a predetermined number of gas injection ports 12, thermocouples 13, and ten conducting terminals 11 arranged at the numbers and positions based on various evaluation levels. , And fixed to the side wall 9 also made of SUS304 by screw tightening to prepare the support 7. At this time, a gas supply path to the gas injection ports 12 is connected to each gas injection port 12 one by one, and each gas injection port 1
2, the diameter was 1.0 mm, and the distance from the gas injection port 12 to the soaking plate 2 was 3.0 mm. Also, two multilayer structure parts 1
0, the distance from the uppermost multilayer structure 10 to the heat equalizing plate 2 was 8 mm, and the distance from the lower multilayer structure 10 to the heat equalizing plate 2 was 15 mm.

Thereafter, the heat equalizing plate 2 is placed on the support 7, and a bolt 16 is passed through the outer periphery of the heat equalizing plate 2, and the heat insulating portion 17 is interposed so that the heat equalizing plate 2 does not directly contact the support 7. Then, the wafer heating apparatus 1 was obtained by elastically fixing the nut 20 by screwing the elastic body 18 and the washer 19 from the side of the support 7 side.

The positions of the gas injection ports 12 are set at substantially equal intervals within a concentric circle of 95%, 85%, and 75% with respect to the center portion and the diameter of the heat equalizing plate 2, and for comparison. The one without the gas injection port 12 was prepared.

As the evaluation conditions, the power supply section 6 of each wafer heating device 1 was energized and adjusted so that the temperature variation on the surface of the wafer W at 250 ° C. was maintained at ± 0.5 ° C.
, The temperature drops to 50 ° C. and stabilizes.
The time until the temperature variation on the surface became ± 0.5 ° C. was evaluated.

Regarding the temperature variation on the surface of the wafer W,
On the wafer surface, 1 / 3A and 2
A total of 9 temperature measuring elements were installed every 90 degrees at a radius of / 3 A to measure the temperature.

Each of the evaluation criteria is such that the cooling time can be reduced to 20 minutes or less compared to the cooling time of 33 minutes although the gas injection port 12 is not formed. Those that did not exist were regarded as OK.
The evaluation conditions and results are as shown in Table 1.

[0079]

[Table 1]

As can be seen from Table 1, first, the gas injection port 1
No. 2 not formed Sample No. 1 required 33 minutes to stabilize from 250 ° C. to 50 ° C. Gas injection port 1
No. 2 provided only in the center part. 2 indicates that the cooling time is 29 due to insufficient cooling and the gas injection port 12 is
No. 8 were installed at substantially equal intervals in a range having a diameter of 5 to 95%. 3, No. In No. 4, only the outer peripheral portion of the heat equalizing plate 2 was cooled first, and the cooling of the central portion was delayed, and the time required for the temperature variation after cooling to stabilize to ± 0.5 ° C. was long. Similarly, the gas injection port 12 is set to 85 to 95 of the heat equalizing plate 2.
N installed at approximately equal intervals in a range having a diameter of
o. 15, No. 16 also had a slow cooling time. Moreover, no. 4, no. 15, No. In No. 16, since the outer peripheral portion was selectively cooled, cracks occurred in the heat equalizing plate 2 itself due to thermal stress (heat shock) generated at the time of cooling, so that the wafer heating device 1 could not function.

On the other hand, the N
o. In Nos. 5 to 14, the cooling time could be reduced to 50% or less, and good results were obtained.

As described above, the wafer heating apparatus 1 provided with at least three or more gas injection ports 12 for cooling the soaking plate 2 in a range having a diameter of 85% of the soaking plate 2 As a result, the cooling time can be reduced to 30 minutes or less as compared with the wafer heating apparatus 1 having no gas injection port 12.

Example 2 A heat equalizing plate 2 and a wafer heating device 1 were manufactured in the same manufacturing method as in Example 1. As a second embodiment, the position of the gas injection port 12 is set to 85%, 75% with respect to the center portion and the diameter of the soaking plate 2.
% Concentric circles, three types arranged at substantially equal intervals, ones concentrated in half of the multilayer structure part 10, and ones arranged randomly.

As the evaluation conditions, the power supply section 6 of each wafer heating device 1 was energized and adjusted so that the temperature variation on the surface of the wafer W at 250 ° C. was maintained at ± 0.5 ° C.
After the temperature of the heat equalizing plate 2 is changed to 50 ° C., the temperature is cooled at the arrangement of the gas injection ports 12, and the cooling temperature of the surface of the wafer W when the central temperature of the wafer W reaches 100 ° C. The variation and the temperature stabilization time until the wafer W temperature became 50 ° C. ± 0.5 ° C. were evaluated.

Regarding the temperature variation on the surface of the wafer W,
In the same manner as in Example 1, a total of nine temperature measuring elements were installed on the wafer surface at a radius of 1 / 3A and a radius of 2 / 3A with respect to the center and the wafer radius A every 90 degrees, and the temperature was measured. The flow rate of the cooling gas to each gas injection port 12 at that time was adjusted to 60 × 10 ⁻³ m ³ / min.

The evaluation criteria were as follows: when the center temperature of the wafer W reached 100 ° C., the cooling temperature variation in the wafer surface was 10 ° C. or less, and no troubles such as cracks occurred in the heat equalizing plate 2. Those were OK.

The respective evaluation conditions and results are as shown in Table 2.

[0088]

[Table 2]

As can be seen from Table 2, the gas injection holes 12 were concentrated and installed in half of the multilayer structure 10. 2, N
o. Sample No. 5 had a very large cooling temperature variation of 30 ° C. or more, and cracks were considered to be caused by generation of thermal stress (heat shock) in the cooled part and the uncooled part. In addition, No. 1 in which the gas injection ports 12 were randomly installed.
3, No. No. 6, although cracks did not occur,
The cooling temperature varied greatly and did not satisfy the evaluation criteria.

On the other hand, when the gas injection ports 12 were installed at regular intervals, 1, No. 4 has a variation in cooling temperature of 10
A good result was obtained in which the temperature of the wafer W was 50 ° C. ± 0.5 ° C. below 15 ° C. and the stabilization time was 15 minutes or less.

As described above, the wafer heating apparatus 1 in which the gas injection ports 12 for cooling the heat equalizing plate 2 are provided at substantially equal intervals in a range having a diameter of 85% of the heat equalizing plate 2 is provided. Compared with the wafer heating apparatus 1 in which the gas injection ports 12 are partially concentrated and installed, or a random arrangement, the cooling temperature variation can be stabilized within ± 0.5 ° C. in a short time. Obtained.

Example 3 A heat equalizing plate 2 and a wafer heating apparatus 1 were manufactured by the same manufacturing method as in Example 1. As a third embodiment, a gas supply path 15 for supplying a cooling gas to the gas injection port 12 is shown in FIG.
(A) The gas injection port 12 shown in FIG. 1 is used to provide a plurality of gas supply paths 15 in one path in a single arrangement, and a plurality of gas supply paths 15 installed in one path in a plurality of arrangements. The gas flow rate is different between the gas supply path 15 and the single gas supply path 15 in which all the gas injection ports 12 are installed in one path using the gas injection ports 12 shown in FIG. The variability was evaluated. At this time, the diameter of each gas injection port was unified to 1.0 mm.

As the evaluation conditions, a flow meter was attached to each gas injection port 12 and the flow rate of the distributed cooling gas was 60
The total flow rate was given so as to be × 10 ⁻³ m ³ / min. Thereafter, cooling gas was injected for 5 minutes, and the flow value of each flow meter after 5 minutes was measured.

As the respective evaluation criteria, those in which the variation in the flow rate 5 minutes after the start of the cooling gas injection was within 10% of the average flow rate were OK. The evaluation conditions and results are as shown in Table 3.

[0095]

[Table 3]

As can be seen from Table 3, the number of gas injection ports 12 provided in one gas supply path 15 is No. 1,
No. 4, no. Sample No. 7 had a large variation in gas flow rate of 10% or more. In contrast, gas injection port 1
No. 2 is divided so that gas is supplied from a plurality of gas supply paths 15. 2, No. 3, No. 5, no.
6, no. 8, no. 9: ± 10% variation in gas flow rate
And good results were obtained.

The more the gas flow is divided, the greater the variation in flow rate between the divided flow passages due to the pressure loss in the flow passages. Therefore, if possible, increase the number of gas supply paths 15 to reduce the number of gas injection ports 12 More preferably, the number is equal to or less than twice the number of the roads 15.

Example 4 A heat equalizing plate 2 and a wafer heating device 1 were manufactured by the same manufacturing method as in Example 1. For those having a coat layer on the resistance heating element 5, after the heating resistance element 5 is formed, the same glass paste as the insulating layer is printed on the heating resistance element 5 by a screen printing method, and then heated to 150 ° C. After drying the organic solvent to perform a degreasing treatment at 550 ° C for 30 minutes,
Further, by baking at a temperature of 700 to 800 ° C., a coat layer of glass having a thickness of 80 μm was formed.

The support 7 is made of SUS having a thickness of 2.5 mm.
Two multi-layered structures 10 consisting of 304 are prepared, and one of them is substantially concentrically and substantially equidistant at 50% position with respect to the outer diameter of the center part and the heat equalizing plate 2. Four gas injection ports 12 are provided at approximately 50% of the outer diameter of the plate 2 in a substantially concentric and substantially equidistant manner, and a thermocouple 13 and ten conductive terminals 11 are formed at predetermined positions. Side wall 9 made of
Were fixed with screws to prepare the support 7.

At this time, the gas supply path 15 to the gas injection port 12 is connected to each gas injection port 12 one by one, and the distance between the heat equalizing plate 2 and the gas injection port 12 based on various evaluation levels and The diameter of the gas injection port 12 was set. The diameter of the gas injection port 12 was changed by changing only the diameter adjustment cap 22 shown in FIG. 3B, and the same gas injection port 12 itself was used. The distance between the uppermost multilayer structure portion 14 and the soaking plate 2 among the two multilayer structure portions is 8 mm,
The distance from the lower multilayer structure 14 to the heat equalizing plate 2 is 15 m.
m.

The evaluation conditions were as follows. After the power supply section 6 of each wafer heating apparatus 1 was energized and maintained at 250 ° C. for 30 minutes,
The temperature history of keeping the temperature down to 50 ° C and holding for 30 minutes is 1
Cycle evaluation was performed for 500 cycles, and then the resistance change of the resistance heating element 5 and the shedding of the resistance heating element 5 or the coating layer immediately below the cooling gas were immersed in the flaw detection liquid, and confirmed and evaluated with a magnifying glass. . At this time, the temperature of the surface of the wafer W was measured by installing a center on the wafer surface and nine thermocouples at a radius of 1 / 3A and 2 / 3A with respect to the wafer radius A every 90 degrees as in the first embodiment. The temperature was measured.

Each of the evaluation criteria is such that the cooling time is 15 minutes or less with respect to the cooling time of 33 minutes although the gas injection port 12 is not formed, and the resistance heating element 5 or the coat layer immediately under the cooling gas is applied. Was evaluated as 不 具 合 when no problem such as grain shedding occurred, and as × when grain shattering occurred.
In addition, when the cooling time took 16 to 20 minutes, it was marked as Δ.
Further, the resistance change of the resistance heating element 5 is 1% less than the resistance value before the evaluation.
% Is OK, and any change over that is NG.

Table 4 shows the results.

[0104]

[Table 4]

As can be seen from Table 4, first, the gas injection port 1
No. 2 is not formed. No. 1 required 33 minutes for the cooling time from 250 ° C. to 50 ° C. to stabilize. In addition, the distance from the gas injection port 12 to the heat equalizing plate 2 was set to 10 mm. No. 11, the diameter of the gas injection port 12 was set to a size exceeding 3.0 mm. In No. 13, the cooling time was as long as about 20 minutes. In addition, No. 3 having a diameter of 0.3 mm. 2
Means that although the cooling time was as fast as 13 minutes, the gas injection port 1
It was found that, in the cooling section to which the gas of No. 2 hits, the surface of the heating resistor 5 was shed and the resistance value of the heating resistor 5 changed greatly.

On the other hand, the diameter of the gas injection port 12 is set to 0.
No. 5 to 3.0 mm. 5 to 10 means the cooling time is 1
The time was as short as 5 minutes or less, and the particles were good without any shedding of the cooling part.

[0107] Regarding the particle shedding, No. 1 in which a coat layer was formed on the surface of the heating resistor 5 was used. As for Nos. 3 and 4, threshing did not occur, but the cooling time tended to be long.

[0108]

As described above, according to the present invention, one of the main surfaces of the heat equalizing plate made of ceramics is used as a wafer mounting surface, and the other main surface or inside has a heating resistor. In a wafer heating apparatus provided with a power supply portion electrically connected to a heating resistor on the other main surface, a gas injection port for cooling the heat equalizing plate is provided with an outer diameter of 85% of the heat equalizing plate outer diameter. By providing at least three or more wafers within the range of%, it is possible to obtain a wafer heating apparatus which can be cooled in a short time, has no change in resistance even when a temperature history is added, and has excellent performance and reliability.

[0109] Further, the gas injection ports are arranged in at least one or more substantially concentric circles within a range of 85% or less of the outer diameter of the heat equalizing plate, so that the difference in cooling speed is reduced. Even without heating, uniform heating can be performed in a short time even in the next heating.

Further, by providing a plurality of gas supply paths for supplying a cooling gas to the gas injection port,
The cooling gas is uniformly supplied without pressure loss in the passage, and can be cooled uniformly and in a short time.

Further, since a coating layer having a thickness of 40 to 400 μm is formed on the surface of the heating resistor formed on the other main surface, the gas which is partially injected from a gas injection port can be used. This makes it possible to provide a highly reliable wafer heating apparatus that does not damage the heating resistor formed on the main surface.

As a result, in the semiconductor device manufacturing process, for example, a uniform resist film, a uniform semiconductor thin film, and a uniform etching process can be formed on the wafer surface. Was.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a wafer heating apparatus according to the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention.

FIGS. 3A and 3B are cross-sectional views showing gas injection ports in the wafer heating apparatus of the present invention.

FIGS. 4A and 4B are plan views of a wafer heating apparatus according to the present invention.

FIG. 5 is a sectional view showing a conventional wafer heating apparatus.

FIG. 6 is a sectional view showing a conventional wafer heating apparatus.

[Explanation of symbols]

 1: Wafer heating device 2: Heat equalizing plate 3: Placement surface 4: Insulating layer 5: Heating resistor 6: Power supply 7: Support 8: Lift pin 9: Side wall 10: Multilayer structure 11 Conducting terminal 12: Gas Injector 13: Thermocouple 14: Opening 15: Gas supply path W: Semiconductor wafer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 3/68 H01L 21/205 5F046 // H01L 21/205 21/30 567 21/306 21/302 PF Terms (Reference) 3K034 AA02 AA08 AA10 AA15 AA16 AA19 AA34 AA37 BA05 BA15 BB06 BB14 BC04 BC17 CA02 CA14 CA22 CA27 CA32 HA01 HA10 JA01 JA10 3K092 PP20 QA05 QB02 QB20 QB32 QB43 QB64 QB68 QB74 QC75 QC RF17 RF19 RF22 RF26 SS12 SS34 SS45 VV22 VV28 4K030 FA10 KA24 KA26 LA15 5F004 AA16 BA19 BB18 BB25 BB26 BB29 BB30 BC03 BC08 CA09 5F045 BB08 EF11 EJ03 EJ10 EK07 EK09 EK22 EM02 EM09 EM10 EM09 EN04

Claims (8)

[Claims] 1. A heat equalizing plate made of ceramics has one main surface as a mounting surface of a wafer, and has a heating resistor on the other main surface or inside thereof, and a power supply electrically connected to the heating resistor. A gas injection port for cooling the heat equalizing plate at least within a concentric circle having a diameter of 85% of the heat equalizing plate. A wafer heating device comprising at least one wafer heating device. 2. A wafer heating apparatus according to claim 1, wherein said gas injection ports are provided at substantially equal intervals on at least one substantially concentric circle. 3. The wafer heating apparatus according to claim 1, wherein a gas supply path for supplying a cooling gas to said gas injection port comprises a plurality of paths. 4. The wafer heating apparatus according to claim 1, wherein a coating layer having a thickness of 40 to 400 μm is formed on the surface of the heating resistor formed on the other main surface. 5. A gas injection port having a diameter of 0.5 to 3.0 m.
The wafer heating apparatus according to claim 1, wherein m is m. 6. The apparatus according to claim 1, wherein a distance between said gas injection port and said heat equalizing plate is 0.8 to 8.0 mm.
5. The wafer heating device according to any one of 4. 7. The gas injection port has a heat capacity of 0.15 cal /
5. The wafer heating apparatus according to claim 1, wherein the apparatus is made of a metal or ceramic having a temperature of g.degree. C. or less. 8. The wafer heating apparatus according to claim 1, wherein said gas injection port is made of an oxidation-resistant metal such as stainless steel or a metal subjected to an oxidation-resistant treatment such as plating.