JP3771795B2 - Wafer heating device - Google Patents

Description

【００６７】
表１から判るように、Ｎｏ．１に示す比較例のウエハ加熱装置１は、設定バラツキ、オーバーシュートも大きく、昇温は１５０±０．５℃を越えて安定しなかった。これは、該凹部２１の開口部断面積が小さすぎて、熱電対１０の保持にバラツキが生じやすく、また充填材が均一に充填されにくいためと考えられる。
【００６８】
また、Ｎｏ．２０については、該凹部２１の開口部断面積が大きくなりすぎては発熱パターンのギャプが大きくなりすぎて、ウエハＷの均熱性がくずれやすく、設定値のバラツキが大きくなり、オーバーシュートも大きくなった。
【００６９】
更に、Ｎｏ．３については、設定バラツキは基準値内に収り、オーバーシュートは発生しなかったが、検知部が発熱抵抗体５に近いために、検知の応答性が敏感すぎて、早切れ状態となり、目標温度に到達しないまま収束してしまった。
【００７０】
また、Ｎｏ．１６については、検知部がウエハＷの載置面３に近すぎて、応答性が若干遅れるため、オーバーシュートが若干ではあるが、規定を越えてしまった。
【００７１】
更に、Ｎｏ．１７については、設定バラツキは基準値内に収まったが、オーバーシュートが大きくなり、目標温度範囲を越えて、より高い温度で収束した。これは、熱電対１０の素線径が太すぎて熱容量が大きくなり、温度検知の応答性が鈍くなったためと考えられる。
【００７２】
これに対し、本特許の請求範囲内で作製されたウエハ加熱装置１であるＮｏ．２、４〜１３、１５、１７〜１９については、いずれも目標値をクリアーしている。
【００７３】
更に望ましくは、該凹部２１の底面と該熱電対１０の測温接点との距離Ｌを、０ｍｍ≦Ｌ≦１．０ｍｍとすることにより、設定バラツキ及びオーバーシュートが基準値の半分以下に押さえられることが判った。
【００７４】
実施例 ２
ここでは、熱電対１０を設置する凹部２１の形状について検討した。具体的には、図６（ａ）に示すように、凹部２１の底部の断面積Ｓ１に対し開口部の断面積Ｓ２が大きくなるウエハ加熱装置１と、図６（ｂ）に示すように、凹部２１の底部の断面積Ｓ１に対し開口部の断面積Ｓ２が小さくなるように形成したウエハ加熱装置１を作製して評価した。その他の部分は、実施例１と同様にして作製した。
【００７５】
一般的にセラミック基板に止まり穴加工を施す場合、どうしても底部にＲ形状が付いてしまうため、ここでいう底部の面積Ｓ１とは該底Ｒが無いものとして、穴側面の延長上で計算された面積である。同様に開口部の面積Ｓ２についても、開口部のＣ面やＲ面を除外して、穴側面の延長上で計算された面積である。
【００７６】
これらのサンプル及びＮｏ．８のサンプルを常温から２５０℃の昇温サイクルを繰り返し３０００サイクル経過後に、実施例１と同様に、２５０℃設定バラツキ、１５０℃オーバーシュート、昇温安定性を評価した。
【００７７】
昇温サイクル前の結果を基準として、昇温サイクル後の結果が、５０％以上変化しているものをＮＧ、５０％以内であるものをＯＫとした。
【００７８】
結果を表２に示した。
【００７９】
【表２】

【００８０】
表２から判るように、Ｎｏ．２２、２３は、昇温サイクル後の変化量が大きくなっている。これは、開口部の面積Ｓ２の方が底部の面積Ｓ１より大きいため、昇温サイクル時に均熱板２と充填材２２の熱膨張率の差により充填材２２が抜ける方向に変化し、熱電対１０の設置に変化が生じているためと考えられる。これに対して、Ｎｏ．２１、２４、２５は変化量が小さく安定している。これは、開口部の面積Ｓ２が底部の面積Ｓ１より小さいため、昇温サイクル時の熱膨張差により、充填材が抜ける方向に動きにくい為と考えられる。
【００８１】
なお、図７に示すように前記凹部の底面部から開口部の間で部分的に開口部面積より大きな面積を有する部分を形成することにより同様の効果が得られることは言うまでもない。
【００８２】
【発明の効果】
以上のように、本発明によれば、セラミックスからなる均熱板の一方の主面をウエハの載置面とし、他方の主面もしくは内部に発熱抵抗体を有するとともに、該発熱抵抗体と電気的に接続される給電部を前記他方の主面に具備してなるウエハ加熱装置において、前記均熱板の他方の主面に凹部を具備し、先端部に測温接点を備えた熱電対を前記凹部に挿入し、かつ充填材により接着固定してなり、前記凹部の底面部の面積が開口部の面積以上とすることにより、良好なウエハの温度調整ができるようになった。
【図面の簡単な説明】
【図１】本発明のウエハ加熱装置を示す断面図である。
【図２】本発明のウエハ加熱装置の均熱板を示す平面図である。
【図３】本発明のウエハ加熱装置の熱電対設置部を示す断面図である。
【図４】（ａ）、（ｂ）は本発明のウエハ加熱装置の熱電対設置部を示す断面図である。
【図５】本発明のウエハ加熱装置の要部拡大断面図である。
【図６】（ａ）は、比較例のウエハ加熱装置の均熱板凹部を示す断面図であり、（ｂ）は、本発明のウエハ加熱装置の均熱板凹部を示す断面図である。
【図７】本発明のウエハ加熱装置の均熱板凹部の他の実施形態を示す断面図である。
【図８】従来のウエハ加熱装置を示す断面図である。
【図９】従来のウエハ加熱装置の熱電対設置部を示す断面図である。
【符号の説明】
１：ウエハ加熱装置
２：均熱板
３：載置面
４：絶縁層
５：発熱抵抗体
６：給電部
７：支持体
８：弾性体
１０：熱電対
１１：充填材
２１：凹部
２２：充填材
２３：スリーブ
Ｗ：半導体ウエハ
ｔ：厚み[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wafer heating apparatus mainly used for heating a wafer. For example, a semiconductor thin film is formed on a wafer such as a semiconductor wafer, a liquid crystal substrate, or a circuit substrate, or applied to the wafer. It is suitable for forming a resist film by drying and baking a resist solution.
[0002]
[Prior art]
For example, a wafer heating apparatus is used to heat a semiconductor wafer (hereinafter abbreviated as a wafer) in a semiconductor thin film forming process, an etching process, a resist film baking process, and the like in a manufacturing process of a semiconductor manufacturing apparatus. Yes.
[0003]
Conventional semiconductor manufacturing equipment used batch-type processing that forms a plurality of wafers together. To increase processing accuracy as the wafer size increases from 8 inches to 12 inches, In recent years, a method called single wafer processing for processing one sheet at a time has been implemented. However, if the single wafer type is used, the number of processes per process decreases, so that it is necessary to shorten the wafer processing time. For this reason, the wafer support member has been required to improve the heating temperature accuracy at the same time as shortening the heating time of the wafer and speeding up the adsorption and desorption of the wafer.
[0004]
Among these, in forming the resist film on the wafer, one main surface of the soaking plate 32 made of ceramics such as aluminum nitride or alumina as shown in FIG. 8 is used as a mounting surface 33 on which the wafer W is placed. On the other main surface, there is used a wafer heating device 31 having a structure in which a heating resistor 35 and a power feeding portion 36 are installed via an insulating layer 34, and a conduction terminal 37 is pressed and fixed to the power feeding portion 36 by an elastic body 38. It was. The soaking plate 32 is fixed to the support 41 with bolts 47, and a temperature measuring element 40 is inserted into the soaking plate 32, so that the temperature of the soaking plate 32 is kept at a predetermined temperature. In addition, the power supplied from the conduction terminal 37 to the heating resistor 35 is adjusted. In addition, the conduction terminal 37 is fixed to the plate-like structure portion 43 through the insulating layer 39.
[0005]
Support pins 44 inserted into the recesses 45 are installed on the mounting surface 33 of the wafer heating device 31. When the wafer W is mounted on the mounting surface 33, the wafer W is not removed from the mounting surface 33. To be in contact. Then, after placing the wafer W coated with a resist solution on the support pins 44, the heating resistor 35 is heated to heat the wafer W on the mounting surface 33 through the heat equalizing plate 32. The resist solution is dried and baked to form a resist film on the wafer W.
[0006]
Further, as the ceramic material constituting the soaking plate 32, nitride ceramics or carbide ceramics have been used.
[0007]
In addition, regarding the mounting structure of the temperature measuring element 64 shown in FIG. 9, in order to accurately control the temperature of the soaking plate 62, Japanese Patent Application Laid-Open No. 9-45752 describes the influence of heat sinking of the temperature measuring element 64 itself. It is shown that it is preferable to measure the temperature as close to the wafer W as possible. The structure will be described with reference to FIG. 9. A temperature measuring element 64 is inserted in the vicinity of the wafer mounting surface 63 of a metal heat equalizing plate 62. The temperature measuring element 64 has a temperature measuring resistor 66 made of Pt installed in the protective tube 65 so as to be parallel to the mounting surface 63 and a lead wire 67 is connected thereto. Further, a heat transfer cement 68 is filled in a void in the protective tube 65. In particular, when the heating resistor is divided and controlled, accurate temperature control of the heat equalizing plate 62 cannot be performed unless measurement variation is managed at the same time as measurement accuracy. Therefore, such a mounting structure is preferable. It was.
[0008]
[Problems to be solved by the invention]
However,in frontIn the wafer heating apparatus as described above, in the mounting structure of the temperature measuring element 64 as shown in FIG. 9, the temperature measuring element 64 is merely inserted into the heat equalizing plate 62. To improve the heat capacity, there is a problem that the response speed of temperature measurement becomes slow. In particular, when the temperature control is performed by dividing the heating resistor into a plurality of blocks, if the measured temperature of the temperature measuring element 64 varies from block to block, the control from block to block becomes non-uniform, and the temperature of the soaking plate 62 becomes constant. There was a problem that it took a long time.
[0009]
  In particular, in the heat treatment of a chemically amplified resist that has come to be used for miniaturization of semiconductor wiring in recent years, the transient characteristics until the temperature is stabilized when the wafer W is replaced on the soaking plate 62. The temperature variation within the wafer surface is extremely important for the chemical amplification process of the resist after exposure, and more precise and responsive temperature control is required than ever before. However, in the structure as shown in FIG. 9, the temperature measuring element part of the temperature measuring element is attached to a protective tube, a filler, etc., and the heat capacity is increased and the structure is only inserted into the recess of the heat equalizing plate. A decrease in responsiveness due to the presence of voids is inevitable,in frontThere was a problem in the transitional temperature variation at the time of wafer heating and the time required for temperature stabilization.
[0010]
[Means for Solving the Problems]
  The inventorsin frontAs a result of diligent examination of the above problems, one main surface of the soaking plate made of ceramics is used as a wafer mounting surface, and a heating resistor is provided on the other main surface or inside, and the heating resistor is electrically connected to the heating resistor. In the wafer heating apparatus, wherein the other main surface is provided with a power feeding unit to be connected, the other main surface of the soaking plateRecessedHas, AheadA thermocouple with a temperature measuring junction at the endin frontInsert into the recess and adhere and fix with fillerAnd the area of the bottom surface of the recess is equal to or greater than the area of the opening.It was found that the problem can be solved by doing.
[0011]
  Also,One main surface of the heat equalizing plate made of ceramics is used as a wafer mounting surface, and a heat generating resistor is provided on the other main surface or inside, and a power feeding portion electrically connected to the heat generating resistor is provided on the other surface. In the wafer heating apparatus provided on the main surface, the other main surface of the soaking plate is provided with a recess, a thermocouple provided with a temperature measuring contact at the tip is inserted into the recess, and a filler is used. There is a part that has an area larger than the area of the opening part between the opening part and the bottom part of the concave part.It was found that the problem can be solved.
[0012]
  Also,Resin the fillerByin frontI found that I could improve the problem.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0014]
FIG. 1 is a cross-sectional view showing an example of a wafer heating apparatus 1 according to the present invention, one main surface of a soaking plate 2 made of ceramics mainly composed of silicon carbide, boron carbide, boron nitride, silicon nitride or aluminum nitride. Is a mounting surface 3 on which the wafer W is placed, and a heating resistor 5 is formed on the other main surface through an insulating layer 4 made of glass or resin.
[0015]
As the pattern shape of the heating resistor 5, a pattern shape that can heat the mounting surface 3 uniformly, such as a substantially concentric or spiral shape composed of an arc-shaped electrode portion and a linear electrode portion. I just need it. In order to improve the heat uniformity, the heating resistor 5 can be divided into a plurality of patterns.
[0016]
In addition, the heating resistor 5 is formed with a power feeding portion 6 made of a material such as gold, silver, palladium, platinum or the like, and a conduction terminal 7 is pressed and fixed to the power feeding portion 6 via an elastic body 8 to thereby conduct electricity. Is secured.
[0017]
  Further, the bolts 17 are passed through the outer periphery of the heat equalizing plate 2 and the support 11, and the nut 19 is screwed in via the elastic body 8 and the washer 18 from the heat equalizing plate 2 side, thereby elastically attaching to the support 11. It is fixed. As a result, even when the temperature of the soaking plate 2 is changed or the temperature of the soaking plate 2 fluctuates when a wafer is placed on the mounting surface 3 and the support 11 is deformed,in frontThe elastic body 8 absorbs this, thereby preventing the soaking plate 2 from warping and preventing the temperature distribution on the surface of the wafer W during the wafer W heating.
[0018]
The support 11 includes a plate-like structure 13 composed of a plurality of layers and a side wall, and the plate-like structure 13 has a conductive terminal 7 for supplying power to the heating resistor 5 with an insulating material 9. An air injection port (not shown) and a thermocouple holding unit are formed.
[0019]
Furthermore, the embodiment of the present invention will be described in detail with reference to FIGS. FIG. 2 is a plan view of the soaking plate 2 as viewed from the side of the heating resistor 5. The soaking plate 2 has a recess 21 formed in a portion for holding the thermocouple 10 inside each heating resistor 5 block. ing. In the recess 21, as shown in FIG. 3, a temperature measuring unit of the thermocouple 10 is arranged and filled and held by a filler 22 or the like.
[0020]
The material of the thermocouple 10 is Pt / Rh—Pt / Rh, Pt / Rh—Pt, Ni / Cr / Si—Ni / Si / Mg, Ni / Cr—Al / Mn, Ni / Cr— A Cu / Ni system, a Cu-Cu / Ni system, a W-Re system, or the like can be used, and an appropriate one may be selected for the use atmosphere and temperature. For example, when used in the atmosphere at 300 ° C. or lower, a Ni / Cr—Al / Mn system, a Pt / Rh—Pt system, a Ni / Cr—Cu / Ni system, or the like is desirable, and in a reducing atmosphere, Fe-Cu / Ni system or the like is desirable.
[0021]
  Further, as shown in FIGS. 4A and 4B, a temperature measuring contact 10 b is formed at the tip of the thermocouple 10. The temperature measuring contact 10b is desirably formed in a uniform shape by melting and joining by laser welding or the like in order to reduce variation in temperature measurement detection. After the temperature measuring contact, it is drawn out at an appropriate angle to prevent temperature measurement failure due to contact between the strands, but a recess to avoid receiving heat from other than the temperature measuring contact 10b.21It is desirable to make the angle so that it does not touch.
[0022]
In addition, in order to prevent temperature measurement failure due to contact between the strands, it is also important to set an appropriate angle after the temperature measurement contact so that the strands do not contact each other. It is also effective to use a wire itself coated with an insulating material such as a resin coat, a glass coat, or a ceramic coat. Moreover, you may use an insulation sleeve etc. after a filling holding | maintenance part as needed.
[0023]
Further, it is desirable to protect the portion not held by the filler 22 with an insulating sleeve 23 or the like. Moreover, it is also possible to use the wire itself having an insulating coating such as a glass coat or a ceramic coat.
[0024]
FIG. 5 shows details of each part.
[0025]
The area of the opening of the recess 21 is 1 mm.²~ 30mm²Is desirable. The area of the opening of the recess 21 is 1 mm.²If it is smaller, unevenness is likely to occur in the installation of the thermocouple 10 and the filling of the filler 22, and the temperature measurement will vary. 30mm²If it is larger, the gap between the heating resistors 5 becomes larger and the temperature distribution on the surface of the wafer W becomes larger, which is not preferable.
[0026]
Further, the depth d of the recess 21 is preferably set to 1/4 t ≦ d ≦ 3/4 t with respect to the thickness t of the soaking plate 2. If the depth d is less than ¼t, the distance from the wafer mounting surface increases, so that temperature measurement shifts and the wafer cannot be raised to the target temperature. On the other hand, if it exceeds 3 / 4t, the temperature overshoot is excessively increased, which is not desirable.
[0027]
Furthermore, the wire diameter of the thermocouple 10 inserted and installed in the recess 21 is preferably 0.05 mm to 1.0 mm, more preferably 0.1 to 0.5 mm. If the wire diameter is smaller than 0.05 mm, the strength is not strong and the handling is not stable, so that it is easy to cause a displacement when assembled to the concave portion 21 and a stable installation cannot be performed. On the other hand, when the thickness is larger than 1.0 mm, the heat capacity of the thermocouple 10 itself becomes too large, so that heat is drawn through the strands, the temperature detection is delayed, and the overshoot becomes too large.
[0028]
  As a thermocouple, a sheathed thermocouple with an outer diameter of 0.5 mmφ or less is used.in frontIt can also be fixed by the method described above.
[0029]
Furthermore, the filler 22 used to hold the thermocouple 10 in the recess 21 is composed of an inorganic adhesive such as alumina, aluminum nitride, graphite, zirconia, or the like as a main component, or polyimide as a main component. Any of organic adhesives such as the above may be used, but an appropriate one is selected and used according to the operating temperature and environment. As selection criteria, wettability with the soaking plate 2 and thermal expansion coefficient are important, and the thermal expansion coefficient is more preferably in the range of 50% to 200% with respect to the thermal expansion coefficient of the soaking plate 2. . Moreover, about filling, it is desirable to leave it for a while at room temperature after filling, and to carry out defoaming or the like so as to prevent entrainment of bubbles.
[0030]
Further, when a resin is used as the filler 22, the fluidity is better than that of the type of filler 22 in which the powder is dispersed, so that the workability at the time of filling is improved. Moreover, thermal conductivity can be improved by dispersing a filler having high thermal conductivity and electrical insulation. As the type of resin, it is preferable to use a resin having a heat resistant temperature of 300 ° C. or higher, such as polyimide, polyimide amide, and polyamide imide. On the other hand, when an epoxy resin or silicon resin having a heat resistance temperature of 200 ° C. or less is used, the adhesive strength is high, but the resin becomes carbonized and becomes brittle during use, and the thermocouple peels off and an accurate temperature can be measured. Disappear.
[0031]
  Also,in frontWhen using the resin as described above, it is preferable to set the thickness t to 0.1 to 3 mm as shown in FIG. If the thickness t exceeds 3 mm, the resin filler 22 is peeled off due to shrinkage when the resin is cured, or the resin is crystallized during curing and imidization is liable to deteriorate, which is not preferable. On the other hand, if the thickness is 0.1 mm or less, the strength of the resin film is insufficient, and the thermocouple comes off due to the thermal cycle during use.
[0032]
Further, it is more desirable that the distance L between the bottom surface of the recess 21 and the temperature measuring contact 10b of the thermocouple 10 is 0 ≦ L ≦ 1.0 mm. When the distance L exceeds 1 mm, the responsiveness of temperature detection is delayed and the overshoot becomes large, but by setting it to 1.0 or less, the overshoot becomes smaller.
[0033]
Moreover, as for the shape of the recessed part 21, as shown in FIG.6 (b), it is desirable to make the area S1 of a bottom face part more than the area S2 of an opening part. If the area S1 of the bottom portion is smaller than the area S2 of the opening as shown in FIG. 6A, the filler 22 is caused by the difference in thermal expansion between the soaking plate 2 and the filler 22 due to repeated heating and cooling. Moves in the direction of falling out, temperature detection becomes dull and overshoot becomes large.
[0034]
  Alternatively, as shown in FIG. 7, a step 23 having a larger area than the opening can be formed between the bottom surface of the recess 21 and the opening. Further, in FIG.4In the example shown in FIG.4May be convex. If processed in this way, the step 24Can act as an anchor for the filler and prevent a problem that the filler 22 comes off.
[0035]
In addition, when dividing the heating resistor 5 into a plurality of zones and controlling the temperature, it is preferable to increase the number of thermocouples 10 according to the number of zones. Thereby, the temperature of the wafer W can be controlled to a value closer to the actual temperature. In this case, it is particularly necessary to make the individual installation conditions of the thermocouple 10 uniform. This is because if the temperature detection between the individual thermocouples 10 varies, the control of the individual heating resistor 5 blocks varies, which adversely affects the temperature distribution of the wafer during the temperature rise transient.
[0036]
Further, in FIG. 1, the metal support 11 has a side wall portion and a plate-like structure 13, and the plate-like structure 13 has an opening corresponding to 5 to 50% of the area. . In addition, the plate-like structure 13 is also cooled with a conduction terminal 7 for conducting electricity with a power feeding portion 6 for feeding electricity to the heating resistor 5 of the soaking plate 2 and the soaking plate 2 as needed. A gas jet for performing the operation and a thermocouple 10 for measuring the temperature of the soaking plate 2 are installed.
[0037]
In addition, lift pins (not shown) are installed in the support 11 so as to be able to move up and down, and are used for placing the wafer W on the placement surface 3 and lifting it from the placement surface 3. In order to heat the semiconductor wafer W by the wafer heating apparatus 1, the wafer W carried to the upper side of the mounting surface 3 by the unillustrated transfer arm is supported by the lift pins, and then the lift pins are lowered to move the wafer W. Is placed 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 heat equalizing plate 2.
[0038]
At this time, according to the present invention, the soaking plate 2 is made of a silicon carbide sintered body, a boron carbide sintered body, a boron nitride sintered body, a silicon nitride sintered body, or an aluminum nitride sintered body. Because it is formed, deformation is small even when heat is applied, and the plate thickness can be reduced, so that the heating time until heating to a predetermined processing temperature and the cooling time until cooling from the predetermined processing temperature to near room temperature Since it has a thermal conductivity of 60 W / m · K or more, the Joule heat of the heating resistor 5 can be quickly transmitted even with a thin plate thickness, and the mounting surface can be shortened. 3 can be made extremely small. In addition, since it does not react with moisture in the atmosphere to generate gas, even if it is used for applying a resist film on the semiconductor wafer W, it does not adversely affect the structure of the resist film and is fine. Wiring can be formed with high density.
[0039]
By the way, in order to satisfy such characteristics, the thickness of the soaking plate 2 is preferably set to 1 mm to 7 mm. This is because if the plate thickness is less than 1 mm, the plate thickness is too thin, so that the effect as the soaking plate 2 of leveling the temperature variation is small, and the Joule heat variation in the heating resistor 5 remains as it is. This is because it is difficult to equalize the mounting surface 3 because it appears as a temperature variation of 3, and conversely, if the plate thickness exceeds 7 mm, the heat capacity of the heat equalizing plate 2 becomes too large and is heated to a predetermined processing temperature. This is because the heating time up to and the cooling time when changing the temperature become long, and the productivity cannot be improved.
[0040]
Further, in the wafer heating apparatus 1 of the present invention described above in detail, as shown in FIG. 1, a heating resistor 5 is formed on the surface of the soaking plate 2 via an insulating layer 4 to expose the heating resistor 5. Therefore, the resistance value can be adjusted by trimming the heating resistor 5 so that the temperature distribution of the mounting surface 3 becomes uniform according to the use conditions and the like.
[0041]
Moreover, as ceramics which form the soaking | uniform-heating board 2, what has as a main component any one or more of silicon carbide, boron carbide, boron nitride, silicon nitride, and aluminum nitride can be used. As the silicon carbide sintered body, a sintering aid containing boron (B) and carbon (C) as sintering aids for the main component silicon carbide, or a sintering aid for the main component silicon carbide. Alumina (Al₂O_Three) And Yttria (Y₂O_Three) And sintered at 1900 to 2200 ° C., and silicon carbide may be either α-type or β-type.
[0042]
The boron carbide sintered body is obtained by mixing 3 to 10% by weight of carbon as a sintering aid with boron carbide as a main component, and performing hot press firing at 2000 to 2200 ° C. be able to.
[0043]
In the boron nitride sintered body, 30 to 45% by weight of aluminum nitride and 5 to 10% by weight of rare earth element oxide are mixed as a sintering aid with respect to boron nitride as a main component, and 1900 to 2100. A sintered body can be obtained by hot-press firing at ° C. Another method for obtaining a sintered body of boron nitride is to mix and sinter borosilicate glass, but this is not preferable because the thermal conductivity is significantly reduced.
[0044]
The silicon nitride sintered body is composed of 3 to 12% by weight of rare earth element oxide and 0.5 to 3% by weight of Al as a sintering aid with respect to silicon nitride as a main component.₂O_ThreeFurthermore, SiO contained in the sintered body₂SiO in an amount of 1.5 to 5% by weight₂Can be mixed and subjected to hot press firing at 1650 to 1750 ° C. to obtain a sintered body. SiO shown here₂The amount is SiO generated from impurity oxygen contained in the silicon nitride raw material.₂And SiO as impurities contained in other additives₂And intentionally added SiO₂Is the sum of
[0045]
In addition, as an aluminum nitride sintered body, Y is used as a sintering aid for the main component aluminum nitride.₂O_ThreeAnd Yb₂O_ThreeIt is obtained by adding a rare earth element oxide such as CaO and an alkaline earth metal oxide such as CaO as necessary and mixing them well, processing into a flat plate shape, and then firing at 1900 to 2100 ° C. in nitrogen gas.
[0046]
These sintered bodies are used by selecting a material depending on the application. For example, when used for drying a resist film, a nitride reacts with moisture to generate ammonia gas, which cannot be used because it adversely affects the resist film. Further, in the case of a CVD wafer heating apparatus that may be used at a high temperature of about 800 ° C., the boron nitride-based material containing a large amount of glass is deformed during use, so that the soaking property of the soaking plate 2 is reduced. It may be damaged.
[0047]
Furthermore, the main surface opposite to the mounting surface 3 of the heat equalizing plate 2 has a flatness of 20 μm or less and a surface roughness with a center line average roughness from the viewpoint of improving the adhesion to the insulating layer 4 made of glass or resin. It is preferable that (Ra) be polished to 0.1 μm to 0.5 μm.
[0048]
On the other hand, when a silicon carbide sintered body is used as the soaking plate 2, glass or resin is used as the insulating layer 4 that keeps insulation between the soaking plate 2 and the heating resistor 5 having some conductivity. In the case of using glass, if the thickness is less than 100 μm, the withstand voltage is less than 1.5 kV and the insulation cannot be maintained. Conversely, if the thickness exceeds 500 μm, silicon carbide forming the soaking plate 2 Since the thermal expansion difference between the sintered material and the sintered aluminum nitride material 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 μm to 500 μm, and desirably in the range of 150 μm to 400 μm.
[0049]
When the insulating layer 4 is formed on the surface of the soaking plate 2 made of a silicon carbide-based sintered body, the surface is oxidized in advance to obtain 0.01 to 2 μm thick SiO 2₂After the oxide film 12 made of is formed, the insulating layer 4 is further formed on the surface thereof
When the soaking plate 2 is formed of a ceramic sintered body containing aluminum nitride as a main component, the insulating layer 4 made of glass is formed in order to improve the adhesion of the heating resistor 5 to the soaking plate 2. Form. However, when sufficient glass is added in the heating resistor 5 and sufficient adhesion strength is obtained by this, it can be omitted.
[0050]
Next, when a resin is used for the insulating layer 4, when the thickness is less than 30 μm, the withstand voltage is less than 1.5 kV and the insulation cannot be maintained, and the heating resistor 5 is trimmed by laser processing or the like. If the insulating layer 4 is scratched and does not function as the insulating layer 4, and if the thickness exceeds 400 μm, the amount of solvent and moisture generated during baking of the resin increases, and A so-called foam-like peeling portion is formed, and heat transfer is deteriorated due to the presence of the peeling portion, so that the soaking of the mounting surface 3 is inhibited. Therefore, when using resin as the insulating layer 4, it is preferable to form the thickness of the insulating layer 4 in the range of 30 μm to 400 μm, and desirably in the range of 60 μm to 200 μm.
[0051]
Moreover, as resin which forms the insulating layer 4, when the heat resistance of 200 degreeC or more and the adhesiveness with the heating resistor 5 are considered, a polyimide resin, a polyimide amide resin, a polyamide resin, etc. are preferable.
[0052]
As a means for depositing the insulating layer 4 made of glass or resin on the soaking plate 2, an appropriate amount of the glass paste or resin paste is dropped on the center of the soaking plate 2 and stretched by a spin coating method to be uniform. Or after applying uniformly by screen printing, dipping, spray coating, etc., the temperature is 600 ° C. for glass paste and the temperature is 300 ° C. or more for resin paste. Just burn it in. Further, when glass is used as the insulating layer 4, the soaking plate 2 made of a silicon carbide sintered body or a boron carbide sintered body is heated to a temperature of about 1200 ° C. in advance, and the surface on which the insulating layer 4 is deposited is formed. By performing the oxidation treatment, the adhesion with the insulating layer 4 made of glass can be enhanced.
[0053]
Further, as the heating resistor 5 to be deposited on the insulating layer 4, a single metal such as gold (Au), silver (Ag), copper (Cu), palladium (Pd), etc. is directly deposited by vapor deposition or plating. The metal alone or rhenium oxide (Re₂O_Three), Lanthanum manganate (LaMnO)_ThreeA resin paste or glass paste containing an oxide such as) as a conductive material is prepared, printed in a predetermined pattern shape by a screen printing method or the like, and then baked to bond the conductive material 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 crystallized glass is preferably used in order to suppress a change in resistance value due to thermal cycling.
[0054]
However, when silver or copper is used for the heating resistor 5, migration may occur. In such a case, the same material as the insulating layer 4 or the heating resistor 5 so as to cover the heating resistor 5 is used. A protective film made of the same material as the matrix component may be coated with a thickness of about 30 μm.
[0055]
For the soaking plate 2 of the type incorporating the heating resistor 5, it is preferable to use an aluminum nitride sintered body having high thermal conductivity and high electrical insulation. In this case, a raw material containing aluminum nitride as a main component and appropriately containing a sintering aid is mixed sufficiently and then formed into a disk shape. A paste made of W or WC is printed on the surface of the heating resistor 5 in the pattern shape, After another aluminum nitride molded body is stacked and adhered thereon, firing is performed in a nitrogen gas at a temperature of 1900 to 2100 ° C., so that the soaking plate 2 incorporating the heating resistor 5 can be obtained. Conduction from the heating resistor 5 may be performed by forming a through hole 19 in an aluminum nitride base material, filling a paste made of W or WC, and firing the electrode so that the electrode is drawn to the surface. Further, when the heating temperature of the wafer W is high, the power feeding unit 6 applies a paste mainly composed of a noble metal such as Au or Ag on the through hole 19 and bakes it at 900 to 1000 ° C. The oxidation of the resistor 5 can be prevented.
[0056]
  in frontThe glass that forms the insulating layer 4 may be either crystalline or amorphous. For example, when used for resist drying, the heat-resistant temperature is 200 ° C. or higher and in the temperature range of 20 ° C. to 200 ° C. It is preferable to appropriately select and use one having a thermal expansion coefficient in the range of −5 to + 5 × 10 −7 / ° C. with respect to the thermal expansion coefficient of the ceramic constituting the soaking plate 2. That is, if glass having a coefficient of thermal expansion outside the above range is used, the difference in thermal expansion with the ceramic forming the soaking plate 2 becomes too large, so that the soaking plate 2 warps during cooling after baking the glass. This is because defects such as cracks and peeling are likely to occur.
[0057]
【Example】
Example 1
A silicon carbide sintered body having a thermal conductivity of 80 W / m · K is ground to produce a plurality of disc-shaped soaking plates 2 having a plate thickness of 4 mm and an outer diameter of 230 mm. In order to deposit the insulating layer 4 on the main surface, a glass paste prepared by kneading ethyl cellulose as a binder and terpineol as an organic solvent into glass powder is laid by screen printing and heated to 150 ° C. After drying the organic solvent, degreasing treatment was performed at 550 ° C. for 30 minutes, and baking was performed at a temperature of 700 to 900 ° C. to form an insulating layer 4 made of glass having a thickness of 200 μm. Next, in order to deposit the heating resistor 5 on the insulating layer 4, a glass paste to which Au powder and Pt 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. The organic solvent was dried, and after degreasing at 550 ° C. for 30 minutes, baking was performed at a temperature of 700 to 900 ° C. to form the heating resistor 5 having a thickness of 50 μm. The heating resistor 5 has a five-pattern configuration in which the central portion and the outer peripheral portion are divided into four in the circumferential direction. After that, the heat equalizing plate 2 was manufactured by fixing the power supply portion 6 to the heating resistor 5 with a conductive adhesive.
[0058]
In addition, the support 11 is provided with two plate-like structures 13 made of stainless steel having a thickness of 2.5 mm in which an opening is formed in 30% of the main surface, and 10 conductive terminals are provided on one of these plates. 7 was formed at a predetermined position, and fixed to the side wall portion made of stainless steel by screw tightening to prepare a support 11.
[0059]
Thereafter, the concave portion 21 is formed in the substantially central portion of the heat generating pattern forming portion on the support 11, the thermocouple 10 is installed, and the heat equalizing plate 2 held and fixed with an inorganic filler is stacked. The outer peripheral portion was screwed through an elastic body 8 to obtain the wafer heating apparatus 1 of the present invention shown in FIG.
[0060]
Further, the main component is aluminum nitride, and 5% by weight of Y as a sintering aid.₂O_ThreeA heating resistor 5 made of WC is formed in a desired shape on a green sheet made by stacking five 1 mm green sheets containing WC and filled with paste made of WC serving as an electrode lead-out portion. A disc-shaped formed body was cut out from another green sheet formed by adhering 5 mm of another green sheet formed with a via hole, degreased at 800 ° C. in nitrogen gas, fired at 1900-2100 ° C., and disc-shaped nitrided A soaking plate 2 made of aluminum was obtained.
[0061]
And the electric power feeding part 6 which consists of gold paste was formed by the transfer method, and it baked at 900 degreeC. After that, the concave portion 21 is formed in the substantially central portion of the heat generation pattern, the thermocouple 10 is installed, and the heat equalizing plate 2 held and fixed by the inorganic filler is attached to the support 11 on which the conduction terminal 7 having a spring is mounted. The outer periphery was screwed through the elastic body 8.
[0062]
Here, the area of the opening of the recess 21 is 0.8 mm.²~ 40mm²In this range, the depth d of the recess 21 is t / 5 ≦ d ≦ 4t / 5 with respect to the thickness t of the soaking plate 2, and the thermocouple wire diameter is 0.05 mm to 1.0 mm. In addition, the distance L from the bottom surface of the concave portion 21 to the temperature measuring contact of the thermocouple 10 was distributed in the range of 0 to 1.5 mm, and the wafer heating apparatus 1 for comparison with the present invention was manufactured.
[0063]
Then, the conductive terminals 7 of the 20 types of wafer heating apparatuses 1 according to the present invention and the comparative example thus obtained were energized and held at 250 ° C., and the wafer surface placed on the mounting surface 3 was The set temperature of the temperature controller is corrected for each control channel of each heating pattern so that the temperature variation of the total of 7 points of 6 division points 6 points on the circumference of the wafer radius and the center of the temperature distribution is within 1 ° C. And the setting variation was confirmed. In addition, the same set temperature is corrected even at 150 ° C., the wafer is removed and held for 60 minutes or more only with the heating device, and then the wafer W maintained at room temperature is put into the heating device and placed on the mounting surface 3. The overshoot of the wafer W until it stabilizes to 150 ° C and the temperature rise stabilization time until it stabilizes to 150 ± 0.5 ° C are measured as transient performance evaluations 5 times for each sample, and the maximum value is measured. It was.
[0064]
As an evaluation standard, a wafer having a set temperature variation of 5 ° C. or less when the wafer temperature is 250 ° C. is determined to be OK, and a wafer having a temperature variation of more than NG is determined to be NG. As for transient performance evaluation, overshoot was set to OK at 1.5 ° C. or lower, and NG at higher temperature. Furthermore, with regard to the temperature rise stabilization time, the one that stabilizes to 150 ± 0.5 ° C. in 30 to 50 seconds is determined to be OK, and the temperature after stabilization becomes less than 149.5 ° C. or exceeds 150.5 ° C. A sample that was stable at 150 ± 0.5 ° C. but took 50 seconds or more was defined as NG.
[0065]
Each result is as shown in Table 1.
[0066]
[Table 1]

[0067]
As can be seen from Table 1, no. In the wafer heating apparatus 1 of the comparative example shown in FIG. 1, the set variation and the overshoot were large, and the temperature rise exceeded 150 ± 0.5 ° C. and was not stable. This is presumably because the cross-sectional area of the opening of the recess 21 is too small and the holding of the thermocouple 10 tends to vary, and it is difficult to uniformly fill the filler.
[0068]
No. For No. 20, if the sectional area of the opening of the recess 21 becomes too large, the gap of the heat generation pattern becomes too large, so that the heat uniformity of the wafer W tends to break down, the set value varies greatly, and the overshoot also increases. It was.
[0069]
Furthermore, no. As for No. 3, the set variation was within the reference value and no overshoot occurred, but the detection part was close to the heating resistor 5, so that the detection response was too sensitive, and the target was quickly cut off. It converged without reaching the temperature.
[0070]
No. For No. 16, since the detection unit was too close to the mounting surface 3 of the wafer W and the response was slightly delayed, the overshoot was slightly over the limit.
[0071]
Furthermore, no. With respect to 17, the set variation was within the reference value, but the overshoot increased and converged at a higher temperature beyond the target temperature range. This is considered to be because the wire diameter of the thermocouple 10 is too large, the heat capacity is increased, and the responsiveness of temperature detection becomes dull.
[0072]
On the other hand, No. 1 which is the wafer heating apparatus 1 manufactured within the scope of claims of this patent. As for 2, 4 to 13, 15, and 17 to 19, the target values are all cleared.
[0073]
More desirably, by setting the distance L between the bottom surface of the recess 21 and the temperature measuring contact of the thermocouple 10 to be 0 mm ≦ L ≦ 1.0 mm, the set variation and overshoot can be suppressed to half or less of the reference value. I found out.
[0074]
Example 2
Here, the shape of the recess 21 in which the thermocouple 10 is installed was examined. Specifically, as shown in FIG. 6A, the wafer heating apparatus 1 in which the cross-sectional area S2 of the opening is larger than the cross-sectional area S1 of the bottom of the recess 21, and as shown in FIG. The wafer heating apparatus 1 formed so that the cross-sectional area S2 of the opening is smaller than the cross-sectional area S1 of the bottom of the recess 21 was produced and evaluated. Other portions were produced in the same manner as in Example 1.
[0075]
In general, when a perforated hole is drilled in a ceramic substrate, an R shape is inevitably attached to the bottom. Therefore, the area S1 of the bottom here is calculated on the extension of the side surface of the hole, assuming that there is no bottom R. It is an area. Similarly, the area S2 of the opening is an area calculated on the extension of the hole side surface, excluding the C-plane and R-plane of the opening.
[0076]
These samples and No. The sample No. 8 was subjected to a temperature rising cycle from room temperature to 250 ° C. After 3000 cycles, 250 ° C. set variation, 150 ° C. overshoot, and temperature rising stability were evaluated in the same manner as in Example 1.
[0077]
On the basis of the result before the temperature raising cycle, NG was evaluated when the result after the temperature raising cycle was changed by 50% or more, and OK when the result was within 50%.
[0078]
The results are shown in Table 2.
[0079]
[Table 2]

[0080]
As can be seen from Table 2, no. In 22 and 23, the amount of change after the heating cycle is large. This is because the area S2 of the opening is larger than the area S1 of the bottom, and therefore changes in the direction in which the filler 22 comes out due to the difference in thermal expansion coefficient between the soaking plate 2 and the filler 22 during the heating cycle. This is probably because the installation of 10 has changed. In contrast, no. 21, 24, and 25 have small changes and are stable. This is presumably because the area S2 of the opening is smaller than the area S1 of the bottom, so that it is difficult to move in the direction in which the filler comes out due to the difference in thermal expansion during the heating cycle.
[0081]
It goes without saying that the same effect can be obtained by forming a part having a larger area than the area of the opening part between the bottom part of the concave part and the opening part as shown in FIG.
[0082]
【The invention's effect】
  As described above, according to the present invention, one main surface of the soaking plate made of ceramics is used as a wafer mounting surface, and the other main surface or inside has a heating resistor, and the heating resistor and electrical In the wafer heating apparatus, wherein the other main surface is provided with a power supply section connected to the other, the other main surface of the heat equalizing plateRecessedHas, AheadA thermocouple with a temperature measuring junction at the endin frontInsert into the recess and adhere and fix with fillerAnd the area of the bottom surface of the recess is equal to or greater than the area of the opening.As a result, the wafer temperature can be adjusted satisfactorily.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a wafer heating apparatus of the present invention.
FIG. 2 is a plan view showing a soaking plate of the wafer heating apparatus of the present invention.
FIG. 3 is a cross-sectional view showing a thermocouple installation part of the wafer heating apparatus of the present invention.
4A and 4B are cross-sectional views showing a thermocouple installation portion of the wafer heating apparatus of the present invention.
FIG. 5 is an enlarged cross-sectional view of a main part of the wafer heating apparatus of the present invention.
6A is a cross-sectional view showing a soaking plate recess of a wafer heating apparatus of a comparative example, and FIG. 6B is a cross-sectional view showing a soaking plate recess of the wafer heating apparatus of the present invention.
FIG. 7 is a cross-sectional view showing another embodiment of the soaking plate recess of the wafer heating apparatus of the present invention.
FIG. 8 is a cross-sectional view showing a conventional wafer heating apparatus.
FIG. 9 is a cross-sectional view showing a thermocouple installation part of a conventional wafer heating apparatus.
[Explanation of symbols]
1: Wafer heating device
2: Soaking plate
3: Placement surface
4: Insulating layer
5: Heating resistor
6: Feeder
7: Support
8: Elastic body
10: Thermocouple
11: Filler
21: recess
22: Filler
23:sleeve
W: Semiconductor wafer
t: thickness

Claims (5)

One main surface of the soaking plate made of ceramics is used as a wafer mounting surface, and has a heating resistor on the other main surface or inside, and a power feeding portion electrically connected to the heating resistor is connected to the other heating surface. in the wafer heating apparatus in accordance with provided on the main surface, provided with a concave portion on the other main surface of the soaking plate and inserting a thermocouple having a temperature measuring contacts first end before Symbol recess, and filling A wafer heating apparatus, characterized in that the area of the bottom surface of the recess is equal to or larger than the area of the opening . One main surface of the soaking plate made of ceramics is used as a wafer mounting surface, and has a heating resistor on the other main surface or inside, and a power feeding portion electrically connected to the heating resistor is connected to the other heating surface. In the wafer heating apparatus provided on the main surface, a concave portion is provided on the other main surface of the soaking plate, a thermocouple provided with a temperature measuring contact at the tip is inserted into the concave portion, and bonded by a filler. fixed becomes, the features and to roux Fine heating device that there is a portion having a partially large area than the opening area between the opening from the bottom portion of the recess. Wafer heating apparatus according to claim 1 or 2, wherein the filler is a resin. Wafer heating apparatus according to claim 3, characterized in that to fix the previous SL thermocouple of resin thickness 0.1 to 3 mm. The distance L between the measuring junction and the bottom surface of the recess before Symbol thermocouple, a wafer heating apparatus according to any one of claims 1-4, characterized in that the 0 ≦ L ≦ 1.0 mm.

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