JP2001210450A - Wafer heating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of cracks due to fatigue in a soaking plate around a brazing material layer caused by a pulling stress applied to the peripheral surface of the brazing material layer by the difference in thermal expansion rate, when a heating resistor and a conductive terminal are connected through the brazing material layer in the wafer heating equipment. SOLUTION: In the water heating equipment which has the wafer installation surface on one side of the main surface of the soaking plate consisting of a ceramic, and having heating resistor on the other mains surface or the inner part, and having a feeder part on the other main surface, the conductive terminal is made to pressed and contacted to the feeder part 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, for forming a semiconductor thin film on a wafer such as a semiconductor wafer, a liquid crystal substrate, or a circuit substrate. It is suitable for forming a resist film by drying and baking the resist solution applied on the wafer.

[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, there has been a demand for the wafer support member to shorten the heating time of the wafer, speed up the suction and desorption of the wafer, and simultaneously improve the heating temperature accuracy.

In forming a resist film on a semiconductor wafer, one main surface of a heat equalizing plate 22 made of ceramics such as aluminum nitride or alumina is placed on a semiconductor wafer as shown in FIG. A wafer heating device 21 having a structure in which a heating resistor 25 is provided on the other main surface via an insulating layer 24 and a conduction terminal 27 is fixed to the heating resistor 25 by a brazing material layer 26. Was used. The heat equalizing plate 22 is fixed to the support frame 27 by screws 32, and a thermocouple 28 is inserted into the heat equalizing plate 22 so that the temperature of the heat equalizing plate 22 is maintained at a predetermined temperature. In this case, the power supplied from the conduction terminal 27 to the heating resistor 25 is adjusted. Further, the conduction terminal 27 is fixed to the plate-like structure 31 via an insulating layer.

The mounting surface 23 of the wafer heating device 21
After the wafer W coated with the resist solution is placed thereon, the heating resistor 25 is heated to heat the wafer W on the mounting surface 23 via the soaking plate 22, and the resist solution is dried and baked. Thus, a resist film is formed on the wafer W.

[0006] As shown in FIG.
Is built into the heat equalizing plate 22, and the heat equalizing plate 2
2. A wafer heating device 21 having a metallization 33 provided on the surface of the substrate 2, a conduction terminal 27 provided inside the metallization 33 via a brazing material layer 26, and a support portion 29 for supporting the heat equalizing plate is also known.

As an example of such a wafer heating device 21, there is, for example, a wafer heating device as disclosed in Japanese Patent Application Laid-Open No. 11-283729. As shown in FIG. 10, the wafer heating apparatus mainly includes a support 29, a heat equalizing plate 22, and a stainless steel plate 33 as a plate-like reflector. The support 29 is a metal member having a bottom (in this case, an aluminum member), and has an opening 34 having a circular cross section on an upper side thereof. Three pin insertion holes 35 for inserting wafer support pins (not shown) are formed in the center of the support 29. Pin insertion hole 3
By raising and lowering the wafer support pins inserted through 5, the wafer W can be transferred to the transfer device or the wafer W can be received from the transfer device. Further, several holes 36 for leading out lead wires are formed in the outer peripheral portion of the bottom portion 29a. A conduction terminal for supplying a current to the heating resistor is inserted into the hole 36.

This heating resistor is for drying a silicon wafer coated with a photosensitive resin at a high temperature (500 ° C. or higher). Heat equalizing plate 22 made of this ceramic
Is formed with a heating resistor, and is supported by the dummy pin 37 in the opening 34 of the support 29.

Further, the heat equalizing plate 22 on which the heating resistor is formed is provided.
Has a circular shape and is designed to have substantially the same diameter as the opening 34 of the support 29. The heat equalizing plate 22 has a multilayer structure, and the heating resistor is buried between the layers. That is,
Here, the heating resistor is not exposed at all from the outer surface of the heat equalizing plate 22. Further, it is described that the conduction terminal 27 involved in conduction of the heating resistor is joined to the heating resistor 25 by a method such as brazing as shown in FIG. Further, it is described that a nitride ceramic or a carbide ceramic is specifically used as a ceramic material constituting the heat equalizing plate 22.

[0010] The power supply section 26 of these wafer heating devices includes:
Since a large voltage is applied for heating or for electrostatic attraction, if there is a contact failure in the electrical contacts, a spark is generated here and the conductive terminal equalizing plate 32 is broken, or the conductive terminal 27 is broken and disconnected. There was a problem of doing. For this reason, the conduction terminal 27 is fixed with a brazing material so as to improve the reliability of the electrical connection.

[0011]

However, in the above-described wafer heating apparatus, the heating resistor formed inside the heat equalizing plate and on one main surface and the conduction terminal are connected via the brazing material layer. In the conventional method, although both are firmly joined, due to the difference in the coefficient of thermal expansion between the ceramic constituting the heat equalizing plate and the brazing material layer and the conduction terminal,
A tensile stress is applied to the outer peripheral surface of the brazing material layer. Further, when the heat equalizing plate is heated, the plate-like structure portion to which the conductive terminal is fixed is not easily heated, and the heat equalizing plate expands first. Therefore, a bending stress is applied to the brazing material layer every time such heating is performed, and there is a problem that a heat equalizing plate around the brazing material layer is fatigued and cracks are generated.

[0012]

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 conductive terminal is pressed against a power supply portion of the heat equalizing plate. The above problem has been solved by providing a wafer heating device characterized by being brought into contact with the wafer.

Further, if the conductive terminals made of brass are simply brought into contact with each other to secure conduction with the power supply unit, the contact surface is oxidized to increase the contact resistance, and the power supply unit is sparked or the heat equalizing plate is heated. However, in the present invention, at least the contact surface of the conductive terminal is formed of at least one selected from Ni, Cr, Au, Ag, stainless steel, and Pt group metal. As a result, contact failure due to oxidation of the contact of the conductive terminal is prevented, and a highly reliable connection can be made.

As a result, it has been found that the stress caused by the temperature difference between the heat equalizing plate and the support can be reduced, and a wafer heating apparatus having good durability can be obtained.

[0015]

Embodiments of the present invention will be described below.

FIG. 1 is a cross-sectional view showing an example of a wafer heating apparatus according to the present invention, in which one main surface of a heat equalizing plate 2 made of ceramics containing silicon carbide, alumina or aluminum nitride as a main component is attached to a wafer W. And a heating resistor 5 formed on the other main surface thereof via an insulating layer 4 made of glass, resin or the like.

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. Further, as the heating resistor 5, gold, silver,
Materials such as palladium and platinum group metals can be used.

Further, a power supply portion 6 made of a material such as gold, silver, palladium, or platinum is formed on the heating resistor 5, and the conductive terminal 7 is pressed against the power supply portion 6 by an elastic body 8 to make contact therewith. Thus, conduction is ensured.

The power supply section 6 thus formed on the heat equalizing plate 2
The connection between the conductive terminal 7 and the conductive terminal 7 is made contact by pressing, so that the heat equalizing plate 22 is configured as compared with the case where the conductive terminal 27 is joined to the heat equalizing plate 22 via the brazing material layer 26 shown in FIG. It is not necessary to consider the thermal stress caused by the difference in the coefficient of thermal expansion between the ceramic to be formed and the brazing material layer 26. As shown in FIG. 1, a difference in expansion between the heat equalizing plate 2 and the support 11 due to a temperature difference can be mitigated by sliding of a contact portion, so that a wafer heating apparatus having good durability against a thermal cycle during use is provided. can do. As the elastic body 8 serving as the pressing means, a coiled spring as shown in FIG. 1 or a leaf spring or the like may be used for pressing.

The conductive terminals 7 are formed by using elastic members 8 of various shapes.
3 to 7 show examples of pressing. FIG. 3 shows that the conductive terminal 7 is pressed by a coil spring as an elastic body 8,
This is an example in which a metal foil 16 is interposed between the power supply unit 6 and the metal foil 16. 4 shows an example using a leaf spring as the elastic body 8, FIG. 5 shows an example using a zigzag leaf spring as the elastic body 8, and FIG.
7 shows an example in which a U-shaped bent leaf spring is used as the elastic body 8, and FIG. 7 shows another example in which a coil spring is used as the elastic body 8. In FIG. 7, the terminal portion 41 of the conduction terminal 7 is provided so as to press the power supply portion 6 by a spring 43 built in the outer cover 45. Also, at the rear end of the terminal 41,
A contact 44 to which a lead wire for supplying power from a power source is connected
Are formed. The energizing terminal 7 is provided with a screw 41
Is fixed to the plate-like structure 13.

The pressing force of these elastic members 8 is set to 0.1.
What is necessary is just to apply a load of 3 N or more to the conductive terminal 7. The reason why the pressing force of the elastic body 8 is set to 0.3 N or more is that the conductive terminal 7 must move in response to a dimensional change due to expansion and contraction of the heat equalizing plate 2 and the support 11. Since the upper conductive terminal 7 is pressed against the power supply unit 6 from the lower surface of the heat equalizing plate, the conductive terminal 7 is prevented from separating from the power supply unit 6 due to friction between the conductive terminal 7 and the sliding portion. .

On the other hand, when the conductive terminal 7 is fixed to the metal support 11 by screwing, the conductive terminal 7 may have poor contact due to thermal deformation of the metal support 11 or, on the contrary, the pressing force may increase. There was a possibility that the heat equalizing plate 2 would be broken. As described above, the electrical connection to the power supply unit 6 by the conduction terminal 7 is made to be a pressing by the elastic body 8, thereby providing a highly reliable electrical connection that does not cause the heat equalizing plate 2 to be damaged. Can be.

It is preferable that the diameter of the conductive terminal 7 on the contact surface side with the power supply section 6 is 1.5 to 4 mm. Further, as the insulating material 9 holding the conductive terminal 7, at a temperature of 200 ° C. or less, a PEEK (polyethoxyethoxyketone resin) material in which glass fibers are dispersed can be used depending on the use temperature. In addition, when used at a higher temperature, a ceramic insulating material 9 made of alumina, mullite, or the like can be used.

At this time, it is preferable that at least the contact portion of the conduction terminal 7 with the power supply portion 6 is formed of a metal made of at least one of Ni, Cr, Ag, Au, stainless steel, and platinum group metals. . Specifically, the conductive terminal 7 itself is formed of the above metal, or the conductive terminal 7
May be provided with a coating layer made of the metal.

Alternatively, as shown in FIG. 3, by inserting a metal foil 16 made of the above-mentioned metal between the conduction terminal 7 and the power supply portion 6, contact failure due to oxidation of the surface of the conduction terminal 7 is prevented, and 2 can be improved in durability. Specifically, N is provided between the power supply unit 6 and the conduction terminal 7.
When a metal foil 16 made of at least one of i, Cr, Ag, Au, stainless steel, and platinum group metals is inserted, the reliability of electrical contact increases, and at the same time, the temperature of the heat equalizing plate 2 and the temperature of the support 11 are increased. The dimensional difference caused by the difference can be reduced by sliding the surface of the metal foil 16.

If the surface of the conductive terminal 7 is subjected to a breaking process or a sandblasting process to prevent the contact from becoming a point contact by roughening the surface, the contact reliability can be further improved. The wafer heating apparatus 1 adjusts the temperature in the surface of the heat equalizing plate 2 so as to be uniform. However, at the time of heating, replacement of the wafer, and the like, the relationship between the temperature of the heat equalizing plate 2 and the temperature of the supporting body 9 Not constant. Due to this temperature difference, the power supply unit 6 and the conductive terminal 7 often come into contact with each other in a twisted positional relationship. Therefore, when these contacts are flattened, contact failure is likely to occur due to one-sided contact.

The soaking plate 2 is attached to a metal support 11.
It is installed so as to cover the opening. The metal support 11 includes a side wall 12 and a single or multilayer plate-like structure 1.
Three. The plate-like structure 13 includes a heat equalizing plate 2.
A conduction terminal 7 for conducting with a power supply section 6 for supplying power to the heating resistor 5 is provided via an insulating material 9 and an elastic body 8 is provided.
Is pressed against the power supply section 6 on the surface of the heat equalizing plate 2. In addition, the thermocouple 10 is provided on the wafer mounting surface 3 at the center of the heat equalizing plate 2.
The temperature of the heat equalizing plate 2 is adjusted based on the temperature of the thermocouple 10. When the heating resistor 5 is divided into a plurality of blocks and the temperature is individually controlled, a thermocouple 10 for temperature measurement is installed in each block of the heating resistor 5.

The heat equalizing plate 2 may be provided with a gas injection port (not shown) for cooling the heat equalizing plate 2 and an opening for discharging gas. Thus, the soaking plate 2
By providing the cooling mechanism described above, a tact time can be reduced by forming a semiconductor thin film or a resist film on the surface of the wafer W or by etching the surface.

It is preferable that the plate-like structure 13 has two or more layers. If this is a single layer, it takes a long time to achieve uniform heat, which is not preferable. It is desirable that the uppermost layer of the plate-like structure portion 13 be installed at a distance of 5 to 15 mm from the heat equalizing plate 2. This facilitates soaking by the radiant heat between the soaking plate 2 and the plate-like structure portion 13, and
Since there is a heat insulating effect with the other layers, the time required for uniform heating is shortened. Further, at the time of cooling, the gas that has received the heat of the surface of the soaking plate 2 from the gas injection port 12 is sequentially discharged to the outside of the layer, and a new cooling gas can cool the surface of the soaking plate, so that the cooling time can be reduced. .

Further, operations such as mounting the wafer W on the mounting surface 3 and lifting the wafer W from the mounting surface 3 are performed by lift pins (not shown) which are installed in the support 7 so as to be able to move up and down. The wafer W is held in a state of being lifted from the mounting surface by wafer support pins (not shown) so as to prevent temperature variation due to one-side contact or the like.

In order to heat the wafer W by the wafer heating apparatus 1, the transfer arm 3 (not shown)
Is supported by lift pins (not shown), and the lift pins 8 are lowered to place the wafer W on the mounting surface 3.

Next, the power supply unit 6 is energized to cause the heating 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. When the heat equalizing plate 2 is formed of a silicon carbide-based sintered body or an aluminum nitride-based sintered body, the deformation is small even if heat is applied, and the plate thickness can be reduced, so that the heating time until heating to a predetermined processing temperature is performed. In addition, the cooling time required for cooling from a predetermined processing temperature to around room temperature can be shortened, and productivity can be increased, and at the same time, 50 W / m
-Since it has a thermal conductivity of K or more, the Joule heat of the heating resistor 5 can be quickly transmitted even with a small plate thickness, and the temperature variation of the mounting surface 3 can be extremely reduced.

As the structure of the heat equalizing plate, a structure having a built-in heating resistor 5 may be used as shown in FIG. In this case, the thickness of the heat equalizing plate 2 is preferably 5 to 20 mm. If the thickness of the soaking plate 2 is less than 5 mm,
Since the heat capacity of the heat equalizing plate 2 is too small, the heat removal by the support 29 becomes too large, and the temperature distribution is deteriorated. Also,
When the thickness of the heat equalizing plate 2 is larger than 20 mm, the heat capacity of the heat equalizing plate 2 becomes too large, the time until the temperature is stabilized becomes long, and the tact time of heating and cooling is preferably reduced. Absent.

The temperature of the soaking plate 2 is measured by a thermocouple 10 whose tip is embedded in the soaking plate 2. As the thermocouple 10, from the viewpoint of its responsiveness and workability of holding,
It is preferable to use a sheath-type thermocouple 10 having an outer diameter of 1.0 mm or less. Further, the middle of the thermocouple 10 is held by the plate-like structure portion 13 of the support portion 7 so that no force is applied to the tip portion embedded in the heat equalizing plate 2. The distal end of the thermocouple 10 has a hole formed in the heat equalizing plate 2 and is fixed to the inner wall surface of the cylindrical metal body provided therein by a spring material to improve the reliability of temperature measurement. Preferred for.

As the ceramic forming the heat equalizing plate 2, a sintered body containing silicon carbide, boron carbide, boron nitride, silicon nitride or aluminum nitride as a main component is used.

The silicon carbide sintered body forming the heat equalizing plate 2 is
Boron (B) and carbon (C) are added as sintering aids to silicon carbide as a main component, or alumina (Al
₂ O ₃ ) and a metal oxide such as yttria (Y ₂ O ₃ ) are added and mixed well, processed into a plate shape,
It is obtained by firing at 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, as the boron carbide sintered body, 3 to 10% by weight of carbon is mixed as a sintering aid with boron carbide as a main component, and the mixture is sintered by hot pressing at 2100 to 2200 ° C. You can get the body.

As the boron nitride sintered body forming the heat equalizing plate 2, 30 to 45% by weight of aluminum nitride and 5 to 10% by weight of rare earth are used as sintering aids with respect to boron nitride as a main component. Mix elemental oxides, 1900-2100 ° C
And sintered by hot pressing. As another method for obtaining a sintered body of boron nitride, there is a method in which borosilicate glass is mixed and sintered, but this method is not preferable because the thermal conductivity is significantly reduced.

As the silicon nitride sintered body forming the heat equalizing plate 2, 3 to 12% by weight of a rare earth element oxide and 0.5 to 3 wt. weight%
Of Al ₂ O _3, further mixing SiO ₂ so that 1.5 to 5 wt% as SiO ₂ content in the sintered body, 16
A sintered body can be obtained by performing hot press firing at 50 to 1750 ° C. The amount of SiO ₂ shown here is
Si generated from impurity oxygen contained in silicon nitride raw material
O ₂ and SiO as impurities contained in other additives
₂ and the sum of intentionally added SiO ₂ .

Further, when these wafer heating devices 1 are used for forming a resist film, if a material containing nitride as a main component is used for the heat equalizing plate 2, ammonia gas reacts with atmospheric moisture and the like. In this case, it is preferable to use a heat equalizing plate 2 made of a carbide such as silicon carbide or boron carbide. At this time, it is necessary to prevent the sintering aid from containing a nitride which may react with water to form ammonia or an amine. Thus, fine wiring can be formed on the wafer W at a high density.

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 heat equalizing plate 2, the insulating layer 4 for maintaining insulation between the heat equalizing plate 2 having semiconductivity and the heat generating resistor 5 is made of glass or glass. It is possible to use a resin. Here, when using glass, if the thickness is less than 100 μm, the withstand voltage is 1.5 k
When the thickness is less than V and the insulating property cannot be maintained, and when the thickness exceeds 600 μm, the thermal expansion difference with the silicon carbide sintered body forming the heat equalizing plate 2 becomes too large, so that cracks are generated and insulation occurs. It no longer functions as layer 4. Therefore, when glass is used as the insulating layer 4, the thickness of the insulating layer 4 is 100 μm to 6 μm.
It is preferably formed in the range of 00 μm, and more preferably in the range of 200 μm to 350 μm.

When the heat equalizing plate 2 is formed of a ceramic sintered body containing aluminum nitride as a main component, the heat equalizing plate 2
The insulating layer 4 made of glass is formed in order to improve the adhesion of the heating resistor 5 to the insulating layer 4. 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 properties of the glass forming the insulating layer 4 may be either crystalline or amorphous. The glass has a heat resistant temperature 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.

Next, when a resin is used for the insulating layer 4, if the thickness is less than 30 μm, the withstand voltage falls below 1.5 kV, the insulating property cannot be maintained, and the heating resistor 5 is trimmed by, for example, laser processing. In this case, the insulating layer 4 is damaged and does not function as the insulating layer 4. Conversely, when the thickness exceeds 150 μm, the amount of evaporation of the solvent and water generated during baking of the resin increases, and a foam-like peeling portion called blister is formed between the heat equalizing plate 2 and the presence of this peeling portion. Since the heat transfer becomes worse, the soaking of the mounting surface 3 is hindered. Therefore, when a resin is used as the insulating layer 4, the thickness of the insulating layer 4 is preferably in the range of 30 μm to 150 μm, and more preferably in the range of 60 μm to 150 μm.

When the insulating layer 4 is formed of a resin, polyimide resin, polyimide amide resin, or the like may be used in consideration of heat resistance of 200 ° C. or more and adhesion to the heating resistor 5.
It is preferable to use a polyamide resin or the like.

As a means for applying the insulating layer 4 made of glass or resin on the soaking plate 2, a suitable amount of the glass paste or resin paste is dropped on the center of the soaking plate 2 and spin coating is performed. Stretch and apply uniformly, or apply evenly by screen printing, dipping, spray coating, etc., then at a temperature of 600 ° C. for glass paste and 3 for resin paste.
What is necessary is just to bake at the temperature of 00 degreeC or more. Also, the insulating layer 4
When glass is used as the material, a heat equalizing plate 2 made of a silicon carbide-based sintered body or an aluminum nitride-based sintered body is previously 1200
By heating to a temperature of about ° C. and oxidizing the surface on which the insulating layer 4 is to be adhered, the adhesion with the insulating layer 4 made of glass can be increased.

Further, as the heating resistor 5 to be deposited on the insulating layer 4, a simple metal such as gold (Au), silver (Ag), copper (Cu), palladium (Pd), etc. is formed by vapor deposition or plating. Directly, or the above-mentioned metal simple substance, rhenium oxide (Re ₂ O ₃ ), lanthanum manganate (LaMn)
A conductive metal oxide such as O 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. May be combined with 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 or copper is used for the heating resistor 5, migration may occur. In such a case, the insulating layer 4 covers the heating resistor 5.
A protective film made of the same material as described above may be coated with a thickness of about 30 μm.

The heating resistor 5 is formed into a disk shape after sufficiently mixing, for example, a raw material containing aluminum nitride as a main component and appropriately containing a sintering aid, and pastes W or WC on the surface of the heating resistor 5. , And another aluminum nitride molded body is overlaid thereon and adhered thereto, followed by firing in nitrogen gas at a temperature of 1900 to 2100 ° C. In addition, the heating resistor 5
For conduction from, an electrode may be drawn out to the surface by forming a through hole 19 in an aluminum nitride base material, embedding a paste made of W or WC, and firing the paste. When the heating temperature of the wafer W is high, the power supply unit 6 applies a paste containing a noble metal as a main component such as Au, Ag, etc.
By baking at 00 ° C., oxidation of the internal heating resistor 5 can be prevented.

[0052]

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. A glass paste prepared by kneading ethyl cellulose as a binder and terpineol as an organic solvent with glass powder is laid by screen printing in order to apply the insulating layer 4 to one main surface of each heat equalizing plate 2. Then, the organic solvent is dried by heating to 150 ° C., then subjected to a degreasing treatment at 550 ° C. for 30 minutes, and further baked at a temperature of 700 to 900 ° C.
An insulating layer 4 made of glass and having a thickness of 200 μm was formed.
Next, in order to apply the heating resistor 5 on the insulating layer 4, a glass paste to which Au powder and Pd powder are added as a conductive material is printed in a predetermined pattern shape by a screen printing method, and then heated to 150 ° C. After drying the organic solvent and further performing a degreasing treatment at 550 ° C. for 30 minutes,
By baking at a temperature of 900 ° C., a thickness of 5
A heating resistor 5 having a thickness of 0 μm was formed. The heating resistor 5 has a five-pattern configuration in which a central portion and an outer peripheral portion are divided into four in the circumferential direction.

As shown in FIG. 9, the sample of the comparative example in which the conductive terminal 27 is soldered is
Using a -Cu brazing, it was brazed to the power supply unit 26 at 700 [deg.] C. in a vacuum to prepare the heat equalizing plate 22 with the conducting terminals 27.

Further, in the sample of the embodiment of the present invention which presses the conductive terminal 7 shown in FIG. 1, the power supply unit 6 is fixed to the heating resistor 5 with a conductive adhesive, whereby the heat equalizing plate 2 is manufactured. . Then, as the support 11, two plate-like structures 13 each made of SUS304 having a thickness of 2.5 mm and having an opening formed in 30% of the main surface are prepared, and one of them is provided with a thermocouple 10
Further, ten conductive terminals 7 were fixed at predetermined positions via an insulating layer, and were fixed to the side wall 9 also made of SUS304 by screw tightening to obtain a wafer heating apparatus. Then, the conductive terminal 7 having the structure shown in FIG.

Further, five 1 mm green sheets each containing aluminum nitride as a main component and containing 5% by weight of Y ₂ O ₃ as a sintering aid are laminated to form a 5 mm green sheet. A disk is formed from a resistor 5 formed in a desired shape, another green sheet having via holes 15 and 33 filled with a paste of WC serving as an electrode lead-out portion formed thereon and having a thickness of 5 mm and closely adhered thereto. The shape was cut out, degreased in nitrogen gas at 800 ° C., and fired at 1900 to 2100 ° C. to obtain a disk-shaped soaking plate 2 made of aluminum nitride.

Using the same method as in the wafer heating apparatus 1 made of silicon carbide, a sample was prepared.

The conductive terminals 7 and 27 of the four types of wafer heating devices 1 and 21 thus obtained are energized and held at 250 ° C., and the wafer surfaces placed on the mounting surfaces 3 and 23 6 on the circumference of 1/2 of the wafer radius centered on the temperature distribution of
After confirming that the temperature variation at a total of 7 points of 6 division points is within 1 ° C, the temperature is maintained at 250 ° C for 30 minutes, and then 2 points.
50 cycles of cooling to 0 ° C and holding for an additional 30 minutes
After repeating 0 cycles, the presence or absence of cracks on the wafer surfaces on the surfaces of the heat equalizing plates 2 and 22 was examined by a 20-fold binocular inspection.

The results are as shown in Table 1.

[0059]

[Table 1]

As can be seen from Table 1, as shown in FIG. 9, the conductive terminal 27 was fixed to the heat equalizing plate 22 by the brazing material layer 26. 2 and No. In No. 4, cracks occurred around the brazing material layer 26 of the heat equalizing plate 22. On the other hand, in the embodiment of the present invention in which the conductive terminal 7 is provided so as to press the power supply unit 6, the conductive terminal 7 is pressed. No cracks occurred in the heat equalizing plates 2 of Nos. 1 and 3.

When the conductive terminals 27 are brazed by using the brazing material layer 26 as in the comparative example shown in FIG. 9, heat is applied during cooling immediately after the wafer is placed on the heat equalizing plate 22 or subsequent rapid heating. Due to the heat equalizing plate 22 and the contraction and expansion generated during the cycle, a tensile stress is repeatedly applied to the ceramic body around the brazing material layer 26, and a crack is generated. On the other hand, when the conductive terminals 7 are pressed as in the embodiment of the present invention shown in FIG. 1, the repetitive stress due to heating and cooling of the heat equalizing plate 2 does not occur on the heat equalizing plate 2. Therefore, it is possible to prevent the occurrence of cracks in the heat equalizing plate 2.

Embodiment 2 Here, regarding the method of pressing the conductive terminal 7 against the heat equalizing plate 2, the presence or absence of cracks in the heat equalizing plate 2 after a heat cycle is performed using screw tightening, a plate spring, and a coil spring. confirmed. For screw tightening, 100 μm
Then, an M3 screw was tightened with a tightening torque of 10 N · cm from above, and the conductive sample was fixed to the other terminals by a spring so as to evaluate the pressing force to 1 N / cm ² . Five evaluation samples were produced in the same manner as in Example 1 for each five samples.

The durability of the prepared sample was evaluated in the same manner as in Example 1, and the occurrence of cracks and the change in the surface of the power supply section 6 were confirmed.

Table 2 shows the results.

[0065]

[Table 2]

As can be seen from Table 2, the pressing method used was No. In No. 1, one heat equalizing plate 2 was broken before 500 cycles. On the other hand, the pressing method was N by pressing with a leaf spring and a coil spring.
o. Nos. 2 and 3 indicate that no power was generated in the heat equalizing plate 2
Only small scratches could be seen on the surface.

It was determined that the sample pressed by screwing was not able to absorb the warpage due to the delicate temperature distribution during heating of the heat equalizing plate 2 due to deformation.

Example 3 Here, the material of the conductive terminal 7, the coating of the contact surface of the conductive terminal 7 with the power supply section 6, and the formation of the foil-shaped metal layer 16 inserted between the conductive terminal 7 and the power supply section 6 were performed. Material is Al, Ni, C
The same evaluation as in Example 1 was performed using r, Au, Ag, Pd, stainless steel, and Pt group metal, and the resistance change of the heating resistor formed on the heat equalizing plate 2 was examined. The resistance value of each heating resistor was adjusted to 5Ω by trimming, the amount of change in the resistance value after the test was measured, and this change was evaluated as a change in contact resistance. As evaluation criteria, those with a resistance change of 0.5Ω or more were NG, and those with a resistance change of less than 0.5Ω were OK.

Regarding the formation of the coating layer, the tip of the conductive terminal 7 made of stainless steel was dipped in the paste, and then fired at a temperature of 600 to 1200 ° C. to form the coating layer. For the foil-like structure, a 100 μm-thick metal layer 16 made of each metal material is inserted between the conduction terminal 7 and the power supply section 6, and then the conduction terminal 7 is inserted.
Was pressed by a spring. The conductive terminal 7 was pressed by a coil spring with a load of 1N.

Table 3 shows the results.

[0071]

[Table 3]

As can be seen from Table 3, first, as the material of the conductive terminal 7, No. 1 was formed using brass. 1 indicates a resistance change of 0.
8 Ω, which was not preferable. In contrast, Al, N
Those using i, Cr, Au, Ag, Pd, and Pt, Rh exhibited good resistance changes of 0.3Ω or less. It is considered that since brass contains Cu, Cu was oxidized at a temperature of 250 ° C., and the resistance value was greatly increased.

As for the coating layer, Ni, Cr, A
u, Ag, Pd, Pt, and Rh were used, and the resistance change was good at 0.3Ω or less in all cases. In addition, when a foil-shaped metal layer 16 made of various metals is inserted between the conductive terminal 7 made of stainless steel and the power supply section 6, the N
i, Cr, Au, Ag, Pd, Pt, and Rh were used,
In each case, the resistance change was good at 0.3Ω or less.

Embodiment 4 Here, an elastic body 8 that presses the conduction terminal 7 against the power supply terminal 6
With respect to the pressing force and the conduction terminal 7 after the cycle test.
A change in contact resistance between the power supply terminal 6 and the power supply terminal 6 was examined. The evaluation sample was formed by using a conductive terminal having a coating made of Ag on the contact surface of the stainless steel rod with the power supply unit 6 and applying a pressing force of 0.
Changes were made in the range of 1 to 10.0 N, and changes in contact resistance before and after the cycle test were investigated.

In the cycle test, after the surface temperature of the wafer W placed on the mounting surface 3 was maintained at 250 ° C. for 30 minutes,
500 cycles of cooling to 30 ° C and holding for another 30 minutes.
The cycle was repeated.

The results are shown in Table 4.

[0077]

[Table 4]

As can be seen from Table 4, the pressing force of the conductive terminal 7 was set to 0.2 N or less. In Nos. 1 and 2, the contact resistance after the cycle test was increased by 0.5 to 0.8Ω. On the other hand, in the case of No. 3 where the pressing force was 0.3 N or more. 3-8
Showed no change in the contact resistance, and all exhibited a contact resistance of 0.1 Ω or less. The reason why the contact resistance increased although the pressing force was small is that the heat equalizing plate 2 and the support 11
When the terminal expands and contracts, the conductive terminal 7 pressing the power supply unit 6 must also move.
Is configured to push up the power supply unit from below, so that the conductive terminal loses frictional resistance with the portion supporting the power supply unit, making it difficult to contact the power supply unit.

[0079]

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 having a power supply portion electrically connected to a heating resistor on the other main surface, a conductive terminal is brought into contact with the power supply portion of the heat equalizing plate by pressing, so that the vicinity of the power supply portion is reduced. Cracks are prevented from being generated on the heat equalizing plate, and Ni, Cr, Ag, A
u, stainless steel, and a metal that is not easily oxidized, such as a Pt group metal, can improve the reliability of conduction between the conduction terminal and the power supply unit. It is possible to do.

[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.

FIG. 3 is a sectional view of a conductive terminal portion in the wafer heating device of the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of the conduction terminal in the wafer heating apparatus of the present invention.

FIG. 5 is a sectional view showing another embodiment of the conduction terminal in the wafer heating apparatus of the present invention.

FIG. 6 is a sectional view showing another embodiment of the conduction terminal in the wafer heating apparatus of the present invention.

FIG. 7 is a sectional view showing another embodiment of the conduction terminal in the wafer heating apparatus of the present invention.

FIG. 8 is a sectional view of a conventional wafer heating apparatus.

FIG. 9 is a sectional view of a conventional wafer heating apparatus.

FIG. 10 is an exploded perspective view showing the structure of a conventional wafer heating device.

FIG. 11 is a cross-sectional view of a conductive terminal joint in a conventional wafer heating apparatus.

[Explanation of symbols]

 1: Wafer heating device 2: Heat equalizing plate 3: Mounting surface 4: Insulating layer 5: Heating resistor 6: Power supply unit 7: Conductive terminal 8: Elastic body 10: Thermocouple 11: Support body W: Semiconductor wafer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // H01L 21/205 H01L 21/30 567 21/3065 21/302 B F term (Reference) 3K034 AA02 AA04 AA16 BA06 BB06 BB14 BC12 BC17 CA02 EA04 HA01 HA10 JA10 3K092 PP20 QA05 QC02 QC22 RF03 RF22 RF27 VV31 5F004 AA16 BB18 BB26 BC08 5F045 DP02 DQ10 EK08 5F046 KA04

Claims (6)

[Claims] A power supply electrically connected to one of the main surface of a heat equalizing plate made of ceramics, the main surface being a mounting surface of a wafer, the other main surface or an internal heating resistor and being electrically connected to the heating resistor. A wafer heating device having a portion on the other main surface, wherein a conductive terminal is pressed against and brought into contact with the power supply portion. 2. The wafer heating apparatus according to claim 1, wherein said conductive terminal is elastically pressed. 3. The wafer heating apparatus according to claim 1, wherein a pressing force of said conductive terminal is 0.3 N or more. 4. The conductive terminal according to claim 1, wherein at least a contact portion of the conductive terminal with the power supply portion is made of at least one selected from Ni, Cr, Au, Ag, stainless steel and a platinum group metal. A wafer heating apparatus as described in the above. 5. A semiconductor device comprising: Ni, C
2. The wafer heating apparatus according to claim 1, wherein a metal foil made of at least one selected from the group consisting of r, Au, Ag, stainless steel and a Pt group metal is inserted. 6. The wafer heating apparatus according to claim 1, wherein said ceramics contains silicon carbide, boron carbide, boron nitride, silicon nitride or aluminum nitride as a main component.