JP3904813B2 - Ceramic heater and wafer heating device using the same - Google Patents

Description

【００５８】
表１に示したように、結晶相を生成させないＮｏ．１０は、耐久テストの１８００サイクルでクラックが発生した。
【００５９】
これに対し、Ｚｎ₂ＳｉＯ₄、Ｚｎ₃Ｂ₂Ｏ₆、Ｚｎ₃（ＢＯ₃）₂、Ｚｎ（ＢＯ₂）₂、ＳｉＯ₂の結晶層が発熱抵抗体５中に分散したサンプルＮｏ．１〜９は、すべて５０℃〜３５０℃の繰り返し耐久試験におけるクラックの発生が２０００サイクル以上となり、良好な耐久性を示した。特に、板状体２と発熱抵抗体５の熱膨張率の差が−０．５〜＋３．０×１０^-6／℃の範囲にあるＮｏ．１〜５、７、８は、耐久テストサイクル数が２０００００サイクル以上となり、好適であった。
【００６０】
実施例 ２
ここでは、上記実施例１と同様にサンプルを準備したが、前記発熱抵抗体５がＰｂ、Ｚｎ、Ｂ、Ｂｉ、Ｓｂの少なくとも一種類を含んだ結晶相と、Ａｕ、Ａｇ、Ｐｄ、Ｐｔ族金属のうち少なくとも１種以上を含有し、該発熱抵抗体５の熱膨張係数３．５〜５．５×１０^-6／℃となるようにガラスの組成を変えて調整した。ガラスは亜鉛、硼酸系ガラスとし、熱膨張係数の調整にはＳｉＯ₂、Ｆｅ₂Ｏ₃、ＣａＯ、ＰｂＯを１．０％程度添加することにより行った。
【００６１】
結果を、表２に示した。
【００６２】
【表２】

【００６３】
表２から判るように、発熱抵抗体５の熱膨張係数と板状体２の熱膨張係数の差が−０．５×１０^-6／℃より小さいＮｏ．１および３．０×１０^-6／℃より大きいＮｏ．５は、耐久テストにより３０００サイクル以下でクラックが発生した。
【００６４】
これに対し、発熱抵抗体５の熱膨張係数を板状体２の熱膨張率に対し−０．５〜＋３．０×１０^-6／℃の範囲となるように調整することにより、５０℃〜３５０℃の繰り返し耐久試験におけるクラックの発生を１０００００サイクル以上とすることができた。
【００６５】
実施例 ３
ここでは、上記実施例１と同様にサンプルを準備したが、前記発熱抵抗体５がガラスを含み、このガラスの軟化点が、前記絶縁層４に含まれるガラスの転移点より低いものとそうでないものを作製した。発熱抵抗体５中のガラスは亜鉛、硼酸系ガラスとし、軟化点の調整はＳｉＯ₂、Ｆｅ₂Ｏ₃、ＣａＯ、ＰｂＯを微量添加することにより調整した。この際、発熱抵抗体５の下に位置する絶縁層４のガラスの転移点は６５０℃のものを使用した。ガラスの転移点および軟化点については、ガラス部分をリューターを用いて削り取り、回収した粉末を示差走査熱量分析計により評価した。評価方法については、データの吸熱ピークを確認し、該ピークに至る漸近線を引きその交点を転移点温度および軟化点温度とした。また、データの見方は、低温側から転移点、軟化点の温度と判定し、この温度差を測定した。発熱抵抗体５の部分は、できるだけ金属分を含まない部分を選び、窒素ガスをフローさせながら、金属による影響を抑制して評価した。
【００６６】
結果を、表３に示した。
【００６７】
【表３】

【００６８】
表３に示したように、発熱抵抗体５中のガラスの軟化点が絶縁層ガラスの転移点よりも高いものについては２００００サイクル程度でクラックが発生した。これに対し、発熱抵抗体５に含有されるガラスの軟化点が絶縁層４に使用されるガラスの転移点よりも低いものについては、５０℃〜３５０℃の繰り返し耐久試験におけるクラックの発生が１５００００サイクル以上となり、良好な耐久性を示した。
【００６９】
実施例 ４
ここでは、上記実施例１と同様にサンプルを準備したが、前記発熱抵抗体５が金属成分として、Ｐｔ族金属、Ａｕ、もしくはこれらの合金を主成分としてサンプルを作製した。また、比較用にＡｇ−Ｐｄ系およびＡｇ系の発熱抵抗体５を用いたものを作製して５０〜３５０℃の繰り返し耐久試験を実施した。
【００７０】
結果は、表４に示した。
【００７１】
【表４】

【００７２】
表４から判るように、発熱抵抗体５中の金属成分としてＡｇ−ＰｄやＡｇを用いたＮｏ．７、８は、５００００サイクル以下で発熱抵抗体５にクラックが発生した。これに対し、発熱抵抗体中の金属成分をＰｔ族金属、Ａｕ、もしくはこれらの合金としたＮｏ．１〜６は、５０℃〜３５０℃の繰り返し耐久試験におけるクラックの発生が２５００００サイクル以上となり、良好な耐久性を示した。
【００７３】
実施例 ５
ここでは、実施例１に用いたＮｏ．１〜５、７、８のサンプルを使用して、発熱抵抗体５に通電し、載置面３に載せたウエハの温度が３５０℃になるように調整して、５００時間連続通電し、抵抗変化したものについては、給電部６付近の磁器組成の変化を波長分散型電子顕微鏡（ＥＰＭＡ）による分析で確認した。
【００７４】
結果を、表５に示した。
【００７５】
【表５】

【００７６】
表５から判るように、β−ユークリプタイト（ＬｉＡｌＳｉ₄）を含有するガラスを用いたＮｏ．７、８は、耐久テストにおける抵抗変化が大きく、ＥＰＭＡによりＬｉの移動が確認できたので好ましくない。β−ユークリプタイトはＳｉを含有する鉱物であり、ガラスの熱膨張率を小さくする上では効果があるが、このようにアルカリ金属酸化物を含有するものは電解を印加した際にアルカリ金属のイオン移動が発生するので好ましくないものと判断した。
【００７７】
これに対し、Ｎｏ．１〜５は、良好な耐久性を示した。
【００７８】
【発明の効果】
以上のように、炭化珪素質セラミックスからなる板状体上にＳｉＯ _２ からなる酸化膜を一旦形成し、更にガラスからなる絶縁層を形成させて、その絶縁層の上に形成した発熱抵抗体は、該発熱抵抗体の少なくとも一部にＺｎ、Ｂ、Ｓｉの少なくとも一種類を含む結晶相を含有させることにより、５０℃〜３５０℃の繰り返し耐久試験におけるクラックの発生を２０００サイクル以上とすること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一部拡大断面図である。
【図３】本発明のウエハ加熱装置の一部拡大断面図である。
【図４】本発明のウエハ加熱装置の一部拡大断面図である。
【符号の説明】
１：ウエハ加熱装置
２：板状体
３：載置面
４：絶縁層
５：発熱抵抗体
６：給電部
７：導通端子
８：弾性体
１０：熱電対
１１：支持体
２１：酸化膜
Ｗ：半導体ウエハ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wafer heating apparatus mainly used for heating a wafer, a ceramic heater used therefor, and a method for manufacturing the same, for example, generating a semiconductor thin film on a wafer such as a semiconductor wafer, a liquid crystal substrate, or a circuit substrate. And a wafer heating apparatus suitable for forming a resist film by drying and baking a resist solution applied on the wafer.
[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]
As an example of the wafer heating apparatus as described above, for example, in JP-A-11-40330, “a heating element formed by sintering metal particles on the surface of a plate-like body made of nitride ceramic or carbide ceramic is provided. The heater is characterized by:
[0005]
This ceramic heater is a heater for drying the photosensitive resin formed on the wafer surface. This structure will be described with reference to FIG. 3. Metal particles obtained by sintering one or more metal particles selected from gold, silver, platinum, palladium, lead, tungsten, nickel on the surface of a soaking plate 32 made of ceramics. A heating resistor 35 is formed which includes a sintered body 33 and a metal coating layer 34 made of at least one metal selected from Au, Ag, Pd, Pt, and Ni. Further, it is shown that the metal particle sintered body 34 contains a metal oxide in order to bring the metal particles into close contact with nitride ceramics and carbide ceramics. Further, the conduction terminal 37 is fixed to the heating resistor 35 by the solder 36. Then, it is shown that the wafer W is set apart from the soaking plate 32 by lift pins 39.
[0006]
Aluminum nitride ceramics and silicon carbide ceramics are both suitable as materials for the soaking plate 32 for a semiconductor wafer heating device that requires soaking because both have high thermal conductivity, but are films made of a photosensitive resin. As a material for the soaking plate 32 used in the process of forming the wafer on the wafer W and drying it, silicon carbide ceramics is superior. This is because in the case of aluminum nitride ceramics, aluminum nitride reacts with moisture in the air to generate ammonia gas, which adversely affects the photosensitive resin. Therefore, silicon carbide ceramics are more useful as the soaking plate 32 used in the photosensitive resin drying process.
[0007]
When silicon carbide ceramics is used as a substrate, in order to form a heating resistor portion for heating the wafer W on the silicon carbide ceramics, the silicon carbide ceramics are 1000 ° C. to 1600 ° C. due to the problem of bonding strength. Oxidize for about 1 to 5 hours to form SiO on silicon carbide ceramics₂It is preferable to form a film once, further form an insulating layer made of glass, and form a heating resistor made of a mixture of glass and Pt and Au as conductive species on the insulating layer.
[0008]
[Problems to be solved by the invention]
However, the life of the heating resistor is such that the resistance of the heating resistor starts to increase in about 1000 cycles in a repeated durability test at 50 ° C. to 350 ° C., and in the worst case, the heating resistor is disconnected in 2000 cycles. There was a problem.
[0009]
[Means for Solving the Problems]
  As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by including crystallized glass in the heating resistor. That is,Silicon carbideOn one main surface of a plate made of ceramicsSiO ₂ An oxide film consisting ofA ceramic heater comprising an insulating layer made of glass, a heating resistor on the insulating layer, and the heating resistor containing a crystal phase containing at least one of Zn, B, and Si. It has been found that the above problems can be overcome.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0011]
FIG. 1 is a cross-sectional view showing an example of a wafer heating apparatus having a ceramic heater according to the present invention, in which one main surface of a soaking plate made of a silicon carbide ceramic plate 2 is placed on a mounting surface on which a wafer W is placed. 3 and SiO formed on the other main surface₂A heating resistor 5 is formed on an oxide film 21 made of glass via an insulating layer 4 made of glass, and a power supply unit 6 electrically connected to the heating resistor 5 is provided to constitute a ceramic heater. .
[0012]
The structure of the plate-like body 2 having the ceramic heater of the present invention will be described in detail with reference to FIG. 2 using an example of silicon carbide ceramics. The surface excluding the wafer mounting surface 3 of the plate-like body 2 is made of SiO generated by heat treatment in an oxidizing atmosphere.₂An oxide film 21 made of is formed. An insulating layer 4 made of glass is formed on the oxide film 21, and a heating resistor 5 made of crystallized glass and one or more of Au, Ag, Pd, Pt, Rh, and Ir is formed thereon. The heating resistor 5 is formed with a power feeding portion 6 to constitute a ceramic heater. The ceramic heater is joined to the support 11 and the conductive terminal 7 is pressed and connected to the power feeding unit 6 to constitute a wafer heating apparatus. The wafer W is held away from the placement surface 3 by the support pins 22. This prevents the problem that the temperature distribution is deteriorated due to the wafer W hitting the plate-like body 2.
[0013]
The oxide film 21 is made of Al when the material of the plate-like body 2 is aluminum nitride.₂O_ThreeThus, the oxide film 21 is formed.
[0014]
The heating resistor 5 is made of at least one kind of metal of Au, Ag, Pd, Pt, Rh, Pd and crystallized glass, and at least a part thereof has a crystal phase containing at least one kind of Zn, B, Si. Contains. As a kind of the crystal phase to be generated or dispersed in glass, for example, Zn₂SiO_Four, Zn_ThreeB₂O₆, Zn_Three(BO_Three)₂Zn (BO₂)₂, SiO₂Etc. Since these crystal phases have a low coefficient of thermal expansion, it is possible to extend the life of the heating resistor 5 that has been disconnected in a repeated endurance test of 50 to 350 ° C. of about 2000 cycles to 20000 cycles. is there. In addition, the glass phase including the crystal phase can be reduced in baking temperature by appropriately containing Pb, B, Bi, Sb and the like.
[0015]
  The mixing ratio of glass and metal can be 40:60 to 80:20 by weight. If the ratio is less than 40:60, the amount of glass is too small and the peel strength of the heating resistor 5 is 4 kg / mm. ² Since it becomes the following, it is not preferable. On the other hand, when the ratio is larger than 80:20, the resistance value of the heating resistor 5 in the surface of the plate-like body 2 that becomes a heat-uniform plate after firing tends to vary from block to block or disconnection tends to occur.
[0016]
As a method for crystallizing the glass, for example, once the glass layer is melted and generated, the glass layer is once held for about 1 hour near the crystal nucleation temperature, and after sufficiently generating crystal nuclei, the crystal formation temperature is reached. There is a method of crystallizing glass by raising the temperature.
[0017]
Although it is difficult to measure the amount of crystals produced by crystallization, it is preferable that the amount of transparency of the glass is eliminated. If the generated crystal layer is a needle-like crystal, the strength of the heating resistor 5 can be improved by fiber reinforcement, and the occurrence of cracks can be suppressed. Moreover, even if a microcrack is generated in the glass, it can be expected that the generated crystal can stop the progress of the crack.
[0018]
As the glass used for the heating resistor 5, the heating resistor 5 can be baked at a low temperature of about 700 ° C., and the thermal expansion coefficient is 0.5 to 1.5 with respect to the thermal expansion coefficient of the plate-like body 2. × 10^-6It is necessary to be in the range of / ° C. In general, the relationship between the thermal expansion coefficient of glass and the baking temperature of glass is negatively correlated. When attempting to lower the thermal expansion coefficient, the baking temperature increases, and when attempting to lower the baking temperature, the thermal expansion coefficient tends to increase. It is in. Therefore, it is very difficult to set the thermal expansion coefficient and the baking temperature at the target level at the same time.
[0019]
Therefore, in the present invention, for example, Zn₂SiO_Four, Zn_ThreeB₂O₆, Zn_Three(BO_Three)₂Zn (BO₂)₂, SiO₂The crystal phase having a low thermal expansion coefficient as described above is precipitated or dispersed in the glass to lower the apparent thermal expansion coefficient of the glass. PbO, B₂O_Three, Bi₂O_Three, Sb₂O_ThreeIs rather crystallized and remains in the glass and has the effect of lowering the melting point of the glass. These components are components having a function of reducing the baking temperature without increasing the thermal expansion coefficient of the glass. In addition, the crystal phase in the glass is not particularly limited to those precipitated from the glass phase, but a method of mixing the above crystals in the glass and baking it is used. It doesn't matter.
[0020]
As a crystalline phase having a low thermal expansion coefficient, there is a crystalline phase having a negative thermal expansion coefficient, such as β-eucryptite. In this crystalline phase, Li ions contained in the crystal are applied to the heating resistor 5. It is desirable to use a crystal layer other than β-eucryptite because it may move depending on the voltage and affect the durability.
[0021]
The crystal phase in the glass contained in the heating resistor 5 was identified by X-ray diffraction (manufactured by Rigaku Corporation). The glass transition point and softening point are measured by using a differential scanning calorimeter to measure heat input and output while increasing the temperature, and the asymptotic intersection of the first endothermic shift part of the baseline is the glass point. The softening point was the intersection of asymptotic lines on both sides of the slow exothermic peak that appeared next.
[0022]
The heating resistor 5 contains a glass having a crystal phase containing at least one kind of Zn, B, and Si, and at least one or more of Au, Ag, Pd, and Pt group metal particles. The thermal expansion coefficient of the resistor 5 is −0.5 to + 3.0 × 10 with respect to the thermal expansion coefficient of the plate-like body 2.^-6It is preferable to be in the range of / ° C. In the present invention, one main surface of a plate-like body made of ceramics is used as a wafer mounting surface, and the other main surface is provided with an oxide film 21 and an insulating layer 4 made of glass in this order. Since the heat generating resistor 5 is provided on the insulating layer 4, the thermal expansion coefficient of the heat generating resistor 5 on the insulating layer 4 and the heat generating resistor 5 on the insulating layer 4 increases the life in the repeated durability test at 50 ° C. to 350 ° C. Because it will be.
[0023]
Therefore, the present inventors include the heating resistor 5 containing a crystal phase containing at least one kind of Zn, B, and Si and at least one kind of Au, Ag, Pd, and Pt group metal particles, The thermal expansion coefficient of the heating resistor 5 is 3.4 to 6.9 × 10^-6It was found that the life in a repeated endurance test at 50 ° C. to 350 ° C. can be extended to 200,000 cycles at / ° C.
[0024]
Further, the heating resistor 5 is a crystallized glass containing a crystal phase containing at least one kind of Zn, B, and Si at least in part, and the softening point of the glass part forms a transition of the glass forming an insulating layer. By making it lower than the point, a stronger bonding strength between the heating resistor 5 and the insulating layer 4 can be obtained, and the life in a repeated durability test at 50 ° C. to 350 ° C. can be extended to 220,000 cycles. . The heating resistor 5 is a crystallized glass containing a crystal phase containing at least one kind of Zn, B, and Si at least partially, and the softening point of the glass part is a transition point of the glass forming the insulating layer 4. Even if it is higher, the life in the repeated durability test at 50 ° C. to 350 ° C. can be extended to about 20000 cycles.
[0025]
Further, it is preferable that the heating resistor 5 is mainly composed of a Pt group metal, Au, or an alloy thereof as a metal component. At least a part of the heating resistor 5 contains a crystal phase containing at least one of Zn, B, and Si, and the conductive material is mainly composed of a Pt group metal having a high oxidation resistance, Au, or an alloy thereof. By doing so, the life in a repeated durability test at 50 ° C. to 350 ° C. can be extended to 250,000 cycles. Even when the heating resistor 5 contains a metal other than Pt group metal, Au, or an alloy thereof as a main component, the repeated durability test at 50 ° C. to 350 ° C. as in the invention shown in claim 1 The life in can be extended in the durability test up to about 20000 cycles.
[0026]
The structure of the wafer heating apparatus 1 which is one embodiment of the present invention will be described in detail with reference to FIG. The insulating layer 4 made of glass has a thickness of 10 to 600 μm. When the thickness is 10 μm or less, the electrical insulation between the plate-like body 2 and the heating resistor 5 becomes insufficient. On the other hand, if the thickness is 600 μm or more, glass has a low thermal conductivity coefficient, which is not preferable because heat transfer from the heating resistor 5 to the wafer W mounting surface 3 becomes slow.
[0027]
  In addition, the surface of silicon carbide ceramics, aluminum nitride ceramics and silicon nitride ceramics is not easily wetted and is susceptible to repellency, so it is treated in an oxidizing atmosphere at 1000 to 1600 ° C. for 1 to 5 hours. The acid on the surface of the plate-like body 2Chemical filmWhen 21 is formed, the insulating layer 4 and the heating resistor are easily formed on the surface. In particular, when silicon carbide ceramics are used, the ceramics themselves exhibit semiconductivity, and thus heat treatment as described above is essential before the formation of the insulating layer 4 in order to prevent damage due to current leakage.
[0028]
The flatness of the surface of the insulating layer 4 made of glass is preferably 300 μm or less. If the flatness exceeds 300 μm, the thickness variation when the heating resistor 5 is formed on the surface of the insulating layer 4 increases, and the resistance value variation of the heating resistor 5 increases, which is not preferable.
[0029]
In order to set the flatness of the insulating layer 4 made of glass to 300 μm or less, the flatness of the plate-like body 2 on the side where the insulating layer 4 is applied is set to 300 μm or less, and at the same time, the heat of the ceramics constituting the soaking plate 2 is increased. The coefficient of thermal expansion of the glass is 0 to 0.9 × 10 with respect to the expansion coefficient.^-6It is preferable to make the temperature smaller. This is because the stress due to shrinkage when the glass is sintered is not sufficiently relieved by the heat treatment at the time of baking, and warping that makes the insulating layer 4 side concave is likely to remain. Thus, reducing the warpage of the plate-like body 2 by making the thermal expansion coefficient of the glass smaller than the thermal expansion coefficient of the ceramic forming the plate-like body 2 is effective for improving the flatness.
[0030]
When the flatness of the insulating layer 4 is greater than 300 μm, the heating resistor 5 whose film thickness is controlled in advance is formed on the transfer sheet, and the heating resistor 5 is formed on the insulating layer 4 by transfer. Thus, the thickness of the heating resistor 5 is made uniform so that the plate-like body 2 can be heated uniformly.
[0031]
The insulating layer 4 made of glass is formed by forming a film having a certain thickness by printing or transferring, and heat-treating it at a temperature equal to or higher than the working point of the glass. The coefficient of thermal expansion of the glass is preferably a coefficient of thermal expansion slightly smaller than the coefficient of thermal expansion of the ceramic base material of the soaking plate 2. This is because when the glass is sintered and melted, the stress due to the shrinkage is not sufficiently relaxed, and the stress due to the shrinkage remains in the form of warping, and this is absorbed. As a result, the stress remaining in the glass becomes a compressive stress, so that cracks hardly occur due to thermal stress.
[0032]
Furthermore, it is preferable that the softening point of the glass contained in the heating resistor 5 is lower than the transition point of the glass contained in the insulating layer 4 in order to improve the processing accuracy of the heating resistor 5. Glass is considered to be a highly viscous fluid at temperatures above the transition point. For this reason, the softening point of the glass contained in the heating resistor 5 is made lower than the transition point of the glass contained in the insulating layer 4 so that the insulating layer 4 serving as a substrate is not affected when the heating resistor 5 is baked. To do.
[0033]
Furthermore, the flatness of the plate-like body 2 after being fixed to the support 11 is preferably 80 μm or less, more preferably 40 μm or less. The reason why the flatness of the plate-like body 2 is set to 80 μm or less is that when the temperature of the wafer W is rapidly raised by controlling the distance between the wafer W and the plate-like body 2, the temperature in the wafer W surface is precisely adjusted. This is so that it can be managed.
[0034]
Further, it is preferable that the center portion of the interval between the plate-like body 2 and the wafer W is narrower than the outer peripheral portion. In order to make the temperature distribution of the plate-like body 2 constant, the heat generation distribution of the heating resistor 5 is such that the heat generation amount is larger in the outer peripheral portion where heat can easily escape from the center portion. For this reason, when the temperature is rapidly raised, the temperature rise at the center of the wafer W tends to be delayed. In order to reduce this tendency, it is preferable that the distance between the plate-like body 2 and the wafer W is narrower at the center than at the outer peripheral portion because the responsiveness to the temperature change of the plate-like body 2 becomes faster.
[0035]
Moreover, as ceramics which form the plate-shaped body 2, what has any 1 or more types of silicon carbide, boron carbide, boron nitride, silicon nitride, and aluminum nitride as a main component can be used.
[0036]
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.
[0037]
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.
[0038]
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.
[0039]
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
[0040]
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.
[0041]
Further, the plate-like body 2 is elastic by passing bolts 17 through the outer circumferences of the plate-like body 2 and the support 11 and screwing nuts 19 through the elastic bodies 8 and washers 18 from the plate-like body 2 side. It is fixed to. Thus, even when the temperature of the plate-like body 2 is changed or when the temperature of the plate-like body 2 is changed by placing a wafer on the mounting surface 3, the elastic body 8 absorbs this. As a result, the warpage of the plate-like body 2 can be prevented, and the temperature distribution on the surface of the wafer W during the heating of the wafer W can be prevented.
[0042]
The thermocouple 10 for adjusting the temperature of the plate-like body 2 is installed in the center of the plate-like body 2 in the vicinity of the wafer mounting surface 3, and the temperature of the plate-like body 2 is adjusted based on the temperature of the thermocouple 10. adjust. 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 resistors 5. As the thermocouple 10, it is preferable to use a sheath type thermocouple 10 having an outer diameter of 1.0 mm or less from the viewpoint of responsiveness and workability of holding. Further, the middle portion 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 plate-like body 2. The tip of the thermocouple 10 is formed with a hole in the plate-like body 2, and is pressed and fixed to the inner wall surface of the cylindrical metal body installed therein by a spring material to improve the reliability of temperature measurement. Therefore, it is preferable.
[0043]
Further, when the heating resistor 5 is divided into a plurality of blocks, it is preferable to install a thermocouple 10 for temperature control at the center of each block and control the temperature independently of each other.
[0044]
  As shown in FIG. 4, the holding structure of the thermocouple 10 is formed by forming a concave portion 27 on the main surface of the plate-like body 2 on which the heating resistor 5 is formed, and the thermocouple 10 is formed in the concave portion 27. Thermal conductivity is 65W / in order to improve reliability of temperature measurement.(m ・ K)The thermocouple 10 is installed through the metal foil 23 described above, and the metal chip 22 whose thermal conductivity coefficient is 40 to 170% of that of the plate-like body 2 from above, and the thermal conductivity coefficient is 50 W /(m ・ K)It is preferable that the following pressing jig 24 and support bar 25 are pressed and fixed by an elastic body 26. The diameter of the recess 27 is preferably 3 to 5 mmφ.
[0045]
The support 11 is composed of a plate-like structure 13 and a side wall, and the plate-like structure 13 is provided with a conduction terminal 7 for supplying power to the heating resistor 5 through an insulating material 9 and is not used. The illustrated air injection port and thermocouple holding part are formed. The conduction terminal 7 is configured to be pressed against the power feeding unit 6 by the elastic body 8. The plate-like structure 13 is composed of a plurality of layers.
[0046]
Further, the connection between the power feeding portion 6 formed on the plate-like body 2 and the conduction terminal 7 is a contact by pressing, so that the difference in expansion between the plate-like body 2 and the support 11 due to the temperature difference between them is a contact portion. Therefore, it is possible to provide a wafer heating apparatus with good durability against the thermal cycle during use. As the elastic body 8 as the pressing means, a coiled spring as shown in FIG. 1 or a plate spring or the like may be used for pressing.
[0047]
The pressing force of the elastic body 8 may be such that a load of 0.3 N or more is applied to the conduction terminal 7. The reason why the pressing force of the elastic body 8 is 0.3 N or more is that the conduction terminal 7 must move in response to the dimensional change caused by the expansion and contraction of the plate-like body 2 and the support body 11. Since the upper conductive terminal 7 is pressed against the power feeding portion 6 from the lower surface of the plate-like body 2, the conductive terminal 7 is prevented from being separated from the power feeding portion 6 due to friction with the sliding portion of the conductive terminal 7. is there.
[0048]
Moreover, it is preferable that the diameter of the contact surface side with the electric power feeding part 6 of the conduction terminal 7 shall be 1.5-4 mm. Furthermore, as the insulating material 9 for holding the conductive terminal 7, a PEEK (polyethoxyethoxyketone resin) material in which glass fibers are dispersed can be used at a temperature of 200 ° C. or lower depending on the use temperature. In addition, when used at a temperature higher than that, it is possible to use a ceramic insulating material 9 made of alumina, mullite or the like.
[0049]
At this time, it is preferable that at least the contact portion of the conduction terminal 7 with the power feeding portion 6 is formed of a metal composed of at least one of Ni, Cr, Ag, Au, stainless steel, and platinum group metals. Specifically, the conductive terminal 7 itself can be formed of the above metal, or a coating layer made of the metal can be provided on the surface of the conductive terminal 7.
[0050]
Alternatively, it is possible to prevent contact failure due to oxidation of the surface of the conductive terminal 7 and to improve the durability of the plate-like body 2 by inserting a metal foil made of the above metal between the conductive terminal 7 and the power feeding unit 6. It becomes.
[0051]
Further, if the surface of the conductive terminal 7 is subjected to brazing or sandblasting 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 plate-like body 2 to be uniform, but the relationship between the temperature of the plate-like body 2 and the support body 9 is structurally during heating, when replacing the wafer, and the like. It is not constant. Due to this temperature difference, the power feeding unit 6 and the conductive terminal 7 often come into contact with each other in a twisted positional relationship. Therefore, when these contact points are processed flat, contact with each other tends to occur and contact failure is likely to occur.
[0052]
In order to heat the 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 unillustrated lift pins, and then the lift pins 8 are lowered. Then, the wafer W is placed on the placement surface 3.
[0053]
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 plate-like body 2. When the plate-like body 2 is formed of a silicon carbide sintered body, deformation is small even when heat is applied, and the plate thickness can be reduced. Therefore, the temperature rise time until heating to a predetermined processing temperature and the predetermined processing temperature to room temperature. The cooling time until cooling to the vicinity can be shortened, the productivity can be increased, and the thermal conductivity is 80 W / m · K or more, so even with a thin plate thickness, the Joule heat of the heating resistor 5 Can be transmitted quickly, and the temperature variation of the mounting surface 3 can be made extremely small.
[0054]
【Example】
Example 1
  3 wt% B in silicon carbide raw material₄C and 2% by weight of carbon are mixed with an appropriate amount of binder and solvent, granulated, molded at a molding pressure of 100 MPa, fired at 1900-2100 ° C., and a thermal conductivity of 80 W /(m ・ K)A disk-shaped silicon carbide sintered body having an outer diameter of 230 mm is obtained. Then, after both surfaces are ground, heat treatment is performed at 1400 ° C. for 1 hour, and at the time of cooling, at least from 1000 ° C. to 600 ° C. is cooled at a rate of 300 ° C./hour.₂After forming the film 21 made of the above, the glass paste was printed on one surface and baked at 900 ° C. to form the insulating layer 4. The glass had a coefficient of thermal expansion of 3.8 × 10 −6 / ° C. Furthermore, on the insulating layer, 20% by weight of Au as glass and metal component, 10% by weight of Pt and Zn as a crystalline phase₂SiO₄, Zn₃B₂O₆, Zn₃(BO₃)₂Zn (BO₂)₂, SiO₂A heating resistor paste containing 70% by weight of glass containing a component to be (quartz) was printed and formed into a desired shape by baking at 600 ° C. to 700 ° C. Each crystal phase was identified by X-ray diffraction (manufactured by Rigaku Corporation) after baking the heating resistor 5. At this time, the appearance of the heating resistor 5 was observed.
[0055]
In addition, the sample prepared in this manner is inserted into a 350 ° C. constant temperature bath for 30 minutes and soaked, and the sample is taken out, inserted into a 50 ° C. constant temperature bath for 30 minutes, soaked, and inserted into the 350 ° C. constant temperature bath again. Was applied for 100 cycles, and the appearance of the heating resistor 5 was observed. If there were no cracks, the next 100 cycles were performed and observed again until the cracks occurred. Appearance confirmation was performed with a 20 × binocular microscope to confirm the presence or absence of cracks. Further, five samples were prepared for each condition, and five samples were subjected to a repeated durability test at 50 ° C. to 350 ° C., and the number of cycles in which cracks occurred first was compared.
[0056]
The results are shown in Table 1.
[0057]
[Table 1]

[0058]
As shown in Table 1, no. No. 10 crack occurred in 1800 cycles of the durability test.
[0059]
In contrast, Zn₂SiO_Four, Zn_ThreeB₂O₆, Zn_Three(BO_Three)₂Zn (BO₂)₂, SiO₂Sample No. in which the crystal layer of No. 1 was dispersed in the heating resistor 5 Nos. 1 to 9 showed good durability because the occurrence of cracks in the repeated durability test at 50 ° C. to 350 ° C. was 2000 cycles or more. In particular, the difference in thermal expansion coefficient between the plate-like body 2 and the heating resistor 5 is −0.5 to + 3.0 × 10.^-6No. in the range of / ° C. 1 to 5, 7, and 8 were suitable because the number of endurance test cycles was 200000 cycles or more.
[0060]
Example 2
Here, a sample was prepared in the same manner as in Example 1, but the heating resistor 5 had a crystal phase containing at least one of Pb, Zn, B, Bi, and Sb, and a group of Au, Ag, Pd, and Pt. It contains at least one of the metals, and the thermal expansion coefficient of the heating resistor 5 is 3.5 to 5.5 × 10.^-6It adjusted by changing the composition of glass so that it might become / degreeC. The glass is zinc or boric acid glass, and SiO is used to adjust the thermal expansion coefficient.₂, Fe₂O_Three, CaO and PbO were added by about 1.0%.
[0061]
The results are shown in Table 2.
[0062]
[Table 2]

[0063]
As can be seen from Table 2, the difference between the thermal expansion coefficient of the heating resistor 5 and the thermal expansion coefficient of the plate-like body 2 is −0.5 × 10.^-6No. smaller than / ° C. 1 and 3.0 × 10^-6No. greater than / ° C. In No. 5, cracks occurred in 3000 cycles or less by an endurance test.
[0064]
On the other hand, the thermal expansion coefficient of the heating resistor 5 is −0.5 to + 3.0 × 10 with respect to the thermal expansion coefficient of the plate-like body 2.^-6By adjusting so that it may become the range of / degreeC, the generation | occurrence | production of the crack in a 50 degreeC-350 degreeC repeated durability test was able to be 100000 cycles or more.
[0065]
Example 3
Here, although the sample was prepared similarly to the said Example 1, the said heating resistor 5 contains glass, and it is not so with the thing whose softening point of this glass is lower than the transition point of the glass contained in the said insulating layer 4. Things were made. The glass in the heating resistor 5 is zinc or boric acid glass, and the softening point is adjusted by SiO.₂, Fe₂O_ThreeIt adjusted by adding trace amount of CaO and PbO. At this time, the glass transition point of the insulating layer 4 located under the heating resistor 5 was 650 ° C. Regarding the transition point and softening point of the glass, the glass part was scraped off using a leuter, and the recovered powder was evaluated by a differential scanning calorimeter. Regarding the evaluation method, an endothermic peak in the data was confirmed, an asymptotic line leading to the peak was drawn, and the intersection was defined as a transition point temperature and a softening point temperature. Further, the data was determined by determining the temperature at the transition point and the softening point from the low temperature side and measuring this temperature difference. The portion of the heating resistor 5 was selected as much as possible without containing a metal component, and evaluation was performed while suppressing the influence of the metal while flowing nitrogen gas.
[0066]
The results are shown in Table 3.
[0067]
[Table 3]

[0068]
As shown in Table 3, cracks occurred in about 20000 cycles for the glass having a higher softening point than that of the insulating layer glass in the heating resistor 5. On the other hand, about the thing with the softening point of the glass contained in the heat generating resistor 5 lower than the transition point of the glass used for the insulating layer 4, generation | occurrence | production of the crack in a 50 degreeC-350 degreeC repeated durability test is 150,000. It became more than the cycle and showed good durability.
[0069]
Example 4
Here, a sample was prepared in the same manner as in Example 1, but a sample was prepared using the heating resistor 5 as a metal component and a Pt group metal, Au, or an alloy thereof as a main component. For comparison, an Ag—Pd-based and Ag-based heating resistor 5 was prepared and subjected to a repeated durability test at 50 to 350 ° C.
[0070]
The results are shown in Table 4.
[0071]
[Table 4]

[0072]
As can be seen from Table 4, No. using Ag—Pd or Ag as the metal component in the heating resistor 5. In Nos. 7 and 8, cracks occurred in the heating resistor 5 in 50000 cycles or less. On the other hand, the metal component in the heating resistor is a Pt group metal, Au, or an alloy thereof. In Nos. 1 to 6, the occurrence of cracks in a repeated durability test at 50 ° C. to 350 ° C. was 250,000 cycles or more, indicating good durability.
[0073]
Example 5
Here, No. 1 used in Example 1 was used. Using the samples 1 to 5, 7, and 8, the heating resistor 5 was energized, the temperature of the wafer placed on the mounting surface 3 was adjusted to 350 ° C., and the energization was continued for 500 hours. About what changed, the change of the porcelain composition near the electric power feeding part 6 was confirmed by the analysis by a wavelength dispersive electron microscope (EPMA).
[0074]
The results are shown in Table 5.
[0075]
[Table 5]

[0076]
As can be seen from Table 5, β-eucryptite (LiAlSi_FourNo.) using glass containing 7 and 8 are not preferable because the resistance change in the durability test is large and the movement of Li can be confirmed by EPMA. β-eucryptite is a mineral containing Si, and is effective in reducing the coefficient of thermal expansion of glass. However, those containing an alkali metal oxide as described above are those of alkali metal when electrolysis is applied. Since ion migration occurs, it was judged unfavorable.
[0077]
In contrast, no. 1 to 5 showed good durability.
[0078]
【The invention's effect】
  As aboveSilicon carbideOn a plate-shaped body made of ceramicsSiO ₂ Consist ofOnce the oxide film is formed, an insulating layer made of glass is further formed, and the heating resistor formed on the insulating layer includes at least one kind of Zn, B, and Si in at least a part of the heating resistor. By including a crystal phase containing 200, generation of cracks in a repeated durability test at 50 ° C to 350 ° C is 200.0It became possible to be more than icle.
[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 partially enlarged sectional view of the wafer heating apparatus of the present invention.
FIG. 3 is a partially enlarged sectional view of the wafer heating apparatus of the present invention.
FIG. 4 is a partially enlarged cross-sectional view of the wafer heating apparatus of the present invention.
[Explanation of symbols]
1: Wafer heating device
2: Plate-shaped body
3: Placement surface
4: Insulating layer
5: Heating resistor
6: Feeder
7: Conduction terminal
8: Elastic body
10: Thermocouple
11: Support
21: Oxide film
W: Semiconductor wafer

Claims (5)

An oxide film made of SiO _{2 on} one main surface of a plate-like body made of silicon carbide ceramics, and an insulating layer made of glass thereon , and a heating resistor on the insulating layer, the heating resistor Contains a crystal phase containing at least one of Zn, B, and Si. The heating resistor includes a glass having a crystal phase containing at least one of Zn, B, and Si, and at least one or more of Au, Ag, Pd, Pt, Rh, and Ir. The ceramic heater according to claim 1, wherein the thermal expansion coefficient is in the range of -0.5 to + 3.0 × 10 ^-6 / ° C with respect to the thermal expansion coefficient of the plate-like body.   The ceramic heater according to claim 1, wherein a softening point of glass contained in the heating resistor is lower than a transition point of glass contained in the insulating layer.   2. The ceramic heater according to claim 1, wherein the heating resistor is mainly composed of Pt, Au, or an alloy thereof as a metal component.   5. A wafer heating apparatus, wherein a main surface opposite to a main surface provided with a heating resistor in the ceramic heater according to claim 1 is used as a wafer mounting surface.

Images