JP2006080389A - Wafer supporting member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer supporting member which does not produce many particles even if it is used for a long time in a plasma atmosphere and enables the manufacturing of a semiconductor with high yield. <P>SOLUTION: The wafer supporting member 101 comprises a surface 103 which is one main surface of a platy ceramic body 102 and on which a wafer W is placed; an electrostatic chuck 105 which is provided with electrodes 104a, 104b on the other main surface or an inner part; and a base 107 which is bonded to the electrostatic chuck part 105 via an adhesive layer 111. A recess 114 is formed around the adhesive layer 111 and a tubular protective member 113 presses the recess 114. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wafer support member for adsorbing and holding a wafer such as a semiconductor wafer in a film forming apparatus such as CVD, PVD, sputtering, or a processing apparatus such as an etching apparatus.

  Conventionally, in a semiconductor device manufacturing process, a semiconductor manufacturing apparatus such as a film forming apparatus for forming a thin film on a semiconductor wafer (hereinafter simply referred to as a wafer) or an etching apparatus for performing an etching process is used. A wafer support member is used to hold a semiconductor wafer.

  For example, in the wafer support member 401 shown in FIG. 4, the upper surface of the plate-shaped ceramic body 402 is used as a mounting surface 403 on which the wafer W is placed, and a pair of electrostatic chucking electrodes 404 a and 404 b are formed on the lower surface of the plate-shaped ceramic body 402. The electrostatic chuck portion 405 provided and a base member 407 joined to the lower surface side of the plate-shaped ceramic body 402. The electrostatic chuck portion 405 and the base member 407 are provided on the peripheral portion of the mounting surface 403. A gas supply hole 408 that passes therethrough is formed. After the wafer W is placed on the mounting surface 403, an electrostatic force is generated by applying a voltage between the pair of electrodes for electrostatic attraction 404a and 404b. Is adsorbed on the mounting surface 403, and a heat conductive gas such as He is supplied to the minute gap between the wafer W and the mounting surface 403 from the gas supply hole 408, so It had become a uniform temperature.

  However, when such a wafer support member 401 is repeatedly exposed to various reaction gases used for film formation or etching by plasma in the semiconductor manufacturing process, the wafer support member 401 shown in FIG. The side surface of the layer 411 is eroded by plasma or the like to generate particles, and further erosion may cause dielectric breakdown between the electrode and the plasma. Further, when erosion progresses to the gas supply hole 408, there is a possibility that a heat conductive gas such as He leaks from the side surface of the bonding layer 411 and the surface temperature of the wafer W cannot be made uniform.

  Therefore, in order to solve the above problem, Patent Document 1 discloses an electrostatic chuck in which at least an electrical insulating layer, an electrode, and an adsorption layer are laminated on a metal substrate, and bonding by plasma or the like is performed on the side surface thereof. There has been proposed a wafer support member provided with an anti-erosion insulator to prevent erosion of the layer.

Further, Patent Document 2 proposes a wafer support member in which an exposed portion of an electrode metal layer sandwiched between a dielectric ceramic plate and an electrically insulating pedestal is covered with an insulating material.
JP 2000-114358 A JP-A-8-279550 JP 2003-168725 A

  As an erosion prevention insulator for preventing erosion caused by plasma as shown in Patent Document 1, a film-like material containing a fluorine resin or a silicone resin is bonded and fixed with an adhesive containing a fluorine resin or a silicone resin. It has been proposed, but by repeatedly receiving various reactions due to plasma and etching irradiated from above, the adhesive is eroded, and as a result, the adhesive scatters and causes particles, The plasma may penetrate to the electrode layer and cause dielectric breakdown.

  Moreover, in patent document 2, in order to prevent the plasma from flowing into the brazed portion where the plasma is sandwiched between the dielectric ceramic and the pedestal, an inorganic adhesive, or a silicone resin, a fluororesin, a polyimide is applied to the exposed portion of the brazing material. It has been proposed to fill the resin, but in any case, erosion is caused by repeatedly receiving various reactions by plasma and etching over a long period of time, and as a result, the adhesive scatters and causes particles, There is a problem that the semiconductor layer cannot be produced with a high yield because it may penetrate into the electrode layer and cause dielectric breakdown.

  Therefore, in view of the above problems, the present invention provides an electrostatic chuck portion in which one main surface of the plate-like ceramic body is a mounting surface on which a wafer is placed and an electrode is provided on the other main surface or inside, and the electrostatic chuck portion. And a base part joined via an adhesive layer, a concave portion is formed in the peripheral portion of the adhesive layer, and an annular protective member is disposed so as to press the wall surface in the concave portion. Features.

  Further, the outer side of the annular protective member is the same as or inside the outer side of the electrostatic chuck portion when viewed from a projection plane parallel to the placement surface.

  The open thickness of the annular protective member is 1.02 to 2.0 times the width of the recess.

  The annular protective member is mainly composed of at least one of a fluorine-based resin or a Teflon (registered trademark) -based resin.

  Further, a heat generating part having a built-in resistance heating element is connected between the electrostatic chuck part and the base part through two adhesive layers.

  Further, the peripheral end surfaces of the resistance heating element and the two adhesive layers are part of the bottom surface of the recess.

  The concave portion has a trapezoidal cross section.

  Even if the wafer support member of the present invention is used in a plasma atmosphere, it is possible to provide a wafer support member that can produce semiconductors with a high yield with a small number of particles.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a cross-sectional view showing an example of a wafer support member 101 of the present invention. In this wafer support member 101, one main surface of the plate-like ceramic body 102 is used as a mounting surface 103 on which a wafer W such as a semiconductor wafer is placed, and a pair of electrostatic chucks is attached to the other main surface of the plate-like ceramic body 102. The electrostatic chuck portion 105 having the electrodes 104a and 104b and the base member 107 are bonded with an insulating adhesive layer 111, and the electrostatic chuck portion 105 and the base are placed on the periphery of the mounting surface 103. A plurality of gas supply holes 108 penetrating the member 107 are provided.

As the plate-like ceramic body 102 forming the electrostatic chuck portion 105, a ceramic sintered body mainly composed of at least one of Al ₂ O ₃ , SiC, AlN and Si ₃ N ₄ can be used. Among these, it is preferable to use a ceramic sintered body mainly composed of Al ₂ O ₃ or AlN from the viewpoint of corrosion resistance against halogen-based corrosive gas or plasma. When manufacturing at a lower cost, a ceramic sintered body containing Al ₂ O ₃ as a main component should be used, and when temperature uniformity of the wafer is required, a ceramic sintered body containing AlN as a main component should be used. good.

  Electrostatic adsorption electrodes 104a and 104b formed on the other main surface of the plate-like ceramic body 102 are made of metals such as Ni, Ti, Ag, Cu, Au, Pt, Mo, Mn, alloys thereof, TiN, It is made of a conductive layer made of TiC or WC and having a thickness of 0.1 μm or more, and can be applied by a film forming means such as sputtering, ion plating, vapor deposition, plating, or CVD.

  On the other hand, the base member 107 is made of aluminum, super steel, or a composite material of these metals and a ceramic material, and has a through-hole for taking out the lead wire 110 connected to the electrostatic adsorption electrodes 104a and 104b. ing.

  The wafer support member 101 can place the wafer W on the mounting surface 103 and apply a DC voltage to the electrostatic chucking electrodes 104 a and 104 b to electrostatically attract the wafer W to the mounting surface 103. Then, plasma can be generated above the wafer W to perform various film formation and etching on the wafer W.

  The wafer support member 1 of the present invention is characterized in that a concave portion 114 is formed in the peripheral portion of the adhesive layer, and an annular protective member 113 is disposed in the concave portion 114 so as to press the wall surface thereof. This is to protect the plasma from being directly exposed to the adhesive layer 111 by forming a concave portion 114 below the plate-shaped ceramic body 102 having good plasma resistance and forming an annular protective member 113 in the concave portion 114. Can do. When the annular protective member 113 presses the wall surface of the concave portion 114 around the entire circumference of the concave portion, there is no possibility that a minute gap is generated between the concave portion 114 and the annular protective member 113, and plasma enters the adhesive layer 111. In addition, since the adhesive layer 111 is not corroded, the wafer support member 1 having excellent durability can be provided without generating particles.

  In addition, it is preferable that the outer circumferential side of the electrostatic chuck portion 105 is the same as the inner side of the electrostatic chuck portion 105 or on the inner side when viewed from the projection plane parallel to the mounting surface 103. If the annular protective member 113 is outside the outer side of the electrostatic chuck portion 105, the annular protective member 113 is excellent in plasma resistance because it is directly exposed to the plasma irradiated from above the mounting surface 103. This is because even a material may be eroded and cause particle generation.

  Moreover, in order to press the wall surface of the recessed part 114, it is preferable that the open | release thickness of the cyclic | annular protective member 113 is 1.01-2.0 times the width Wd of a recessed part. More preferably, it is 1.02 to 1.5 times. If the open thickness of the annular protective member 113 exceeds 2.0 times the width Wd of the recess, the force that pushes the recess 114 becomes too large and the peripheral portion of the mounting surface 103 is pushed up, making the mounting surface 103 uniform. There is a risk that the flat surface cannot be maintained. As a result, a gap is generated between the periphery of the wafer W and the mounting surface, and the cooling gas leaks, which may reduce the degree of vacuum in the semiconductor manufacturing apparatus.

  Further, if the open thickness of the annular protective member 113 is smaller than 1.02 times the width Wd of the concave portion, a gap is formed between the annular protective member 113 and the concave portion 114, and there is a possibility that the plasma may easily enter the adhesive layer 111. Because there is.

  In addition, said open | release thickness can be shown by the thickness before pressing the cyclic | annular protection member 113 in the recessed part 114. FIG.

  Specifically, when the cross section of the protective member 113 of the electrostatic chuck 105 holding a silicon wafer having a diameter of 300 mm is a square, the outer diameter of the protective member 113 is 298 mm, and the minimum groove diameter is 285 to 296 mm. The diameter of the protective member before attachment is 260 to 295 mm in inner diameter, and the protective member 113 of the electrostatic chuck 1 of the present invention can be attached by extending the annular protective member 113 having an outer shape of 262 to 297 mm and fitting it into the annular groove. .

  As a material of the annular protective member 113, it is preferable that at least one of a fluororesin and a Teflon (registered trademark) resin is a main component. In particular, polymer materials typified by perfluoroelastomer are preferable among fluororesins. This is a polymer chain having a long carbon-carbon bond, and the polymers are bonded by a chemical bond and can exhibit elasticity. Of course, since it is excellent also in plasma resistance, it is suitable as a protective member. It is preferable that the annular protective member 113 is made of a material having elasticity in such a fluorine-based resin or a Teflon (registered trademark) -based resin.

  Further, as shown in FIG. 2, it is preferable that a heat generating part 215 including a resistance heat generating element 214 is connected between the electrostatic chuck part 205 and the base part 207 via two adhesive layers 211 and 216. With this configuration, since the wafer W can be heated to an arbitrary temperature, the wafer support member 1 can be used in various semiconductor manufacturing processes, and various processes can be performed with one wafer support member 1. It can be used for both purposes.

  Further, it is preferable that the peripheral end surfaces of the heat generating portion 215 and the two adhesive layers 211 and 216 are part of the bottom surface of the concave portion 114. Since the annular protective member 113 is formed so as to cover the peripheral end surfaces of the heating element portion 215 and the two adhesive layers 211 and 216, the adhesive layers 211 and 216 can be prevented from being exposed to plasma. It is preferable. In particular, it is preferable to insert and insert an annular protective member 213 mainly composed of at least one kind of fluorine resin or Teflon (registered trademark) resin into the recess 114.

  In this case, by heating the resistance heating element 214, the adhesive layers 211 and 216 are also heated, so that the plate-like ceramic body 202 is pushed up by thermal expansion, and even if the width Wd of the concave portion increases, an annular protection Since the member 213 is pushed in and inserted, the thickness of the annular protective member 113 is increased by the amount that the width Wd of the recess 114 is increased. Therefore, the annular protective member 113 can protect the heat generating portion 215 and the two adhesive layers 211 and 216 from plasma.

  The annular protective member 113 is press-fitted and fixed in the recess 114. At that time, the recess preferably has a quadrangular cross section as shown in FIG. The cross-sectional shape of the recess 114 as shown in FIG. This is because if the cross-sectional shape is a trapezoid, the sealing area is large, and the effect of preventing the penetration of plasma into the adhesive layer 111 is great. Further, it is desirable that the annular protection member 113 is also formed in accordance with the shape of the recess as shown in FIGS. 3 (a), 3 (b), and 3 (c). A similar effect can be obtained with an O-ring type as shown in FIG. 3D, but a trapezoidal shape or a quadrangular shape is more preferable.

  Further, in the present embodiment, an example of a bipolar type is shown for the electrostatic chuck portion, but a monopolar type electrostatic chuck portion may be used. It goes without saying that the present invention can also be applied to improvements and changes made without departing from the scope of the invention.

  Examples of the present invention will be described below.

  A plate-like ceramic body made of an aluminum nitride sintered body having a diameter of 300 mm and a thickness of 3 mm is prepared, and a Ni film is deposited on the main surface opposite to the mounting surface by a plating method, followed by blasting A pair of electrodes was formed by removing unnecessary portions by processing. Next, a base member provided with an aluminum cooling mechanism was bonded to the opposite side surface of the plate-shaped ceramic body via a bonding layer made of a silicone adhesive.

  Next, the electrostatic chuck portion was formed by grinding the mounting surface side of the plate-like ceramic body to a thickness of 1 mm.

  The recess was formed with a notch in the outer side of the base member and provided between the plate-like ceramic body and the base member. At this time, the dimension of the cross-section of the concave portion was a square having a side of 1 mm, and an annular protective member made of fluorine resin and Teflon (registered trademark) resin was inserted and fixed by pressing.

  Here, in order to confirm the plasma resistance depending on the presence or absence of the annular protective member, a wafer support member having a recess and a wafer support member having no recess were prepared. Further, an annular protective member was fixed on the same surface as the outer side of the electrostatic chuck part, an inner side fixed member, and an outer side of the electrostatic chuck part.

Moreover, the open thickness before attachment of the annular | circular shaped protection member was produced between 0.8 to 2.5 times the width | variety of a recessed part, and it pushed in and inserted in the recessed part, respectively, and fixed, and the wafer support member was produced. Then, this wafer support member was installed in a film forming apparatus, irradiated with oxygen plasma for 100 hours, and then the number of particles of 0.2 μm or more adhering to the wafer was measured and evaluated using a particle counter. The results are shown in Table 1.

  As a result, a concave portion is formed in the peripheral portion of the adhesive layer, and a sample No. in which the annular protective member presses the concave portion. It was found that 1 to 7 showed excellent characteristics with a small number of particles of 98 or less.

  On the other hand, the sample No. 2 has the same width of the recess and the width of the annular protective member when opened. Since No. 8 did not press the inner wall of the recess, a gap was formed between the recess and the annular protective member, and the number of generated particles was 143, which was not preferable.

  In addition, the sample No. in which no recess was formed. No. 10 had a large number of particles of 163 and could not be used as a wafer support member for semiconductors.

  Furthermore, the sample No. of the present invention. Among sample Nos. 1 to 7, the outer side of the annular protective member 103 is the same as the outer side of the electrostatic chuck portion. It was found that 3 to 7 were further excellent in that the number of particles was 53 or less.

  In addition, in the sample No. 2 in which the ratio of the open thickness of the annular protective member Wo to the width Wd of the recess (Wo / Wd) is 1.02 to 2.0. It was found that 4 to 7 were preferable because the number of particles was 18 or less.

  Next, the resistance heating element 214 is bonded and fixed between the electrostatic chuck part 205 and the base member 207 as shown in FIG. 2 with a heating part 215 protected with polyimide and two silicone adhesive layers 211 and 216. A wafer support 205 is fabricated, a recess is formed so as to cover the peripheral end surfaces of the resistance heating element 214 and the two silicone adhesive layers 211 and 216, and the open thickness of the annular protection member 213 is set to the width of the recess. It was produced between 1.02 and 2.0 times, and each was inserted into the recess and fixed.

Then, the number of particles adhering to the wafer after being irradiated with oxygen plasma for 100 hours in a state where the resistance heating element 214 is energized and the surface temperature of the mounting surface 203 is heated to 80 ° C. and 200 ° C. is measured using a particle counter. Went. The results are shown in Table 2.

  As a result, a heat generating part with a built-in resistance heating element is provided in the wafer support member, and even if the wafer W is heated to 80 ° C. or 200 ° C., the number of particles is as small as 19 or less and provides a heat resistant wafer support member. I understood that I could do it.

It is sectional drawing which shows an example of the wafer support member concerning this invention. It is sectional drawing which shows the other example of the wafer support member concerning this invention. (A) (b) (c) (d) is sectional drawing which shows the shape of the various recessed part of the wafer support member concerning this invention. It is sectional drawing which shows an example of the conventional wafer support member. It is sectional drawing which shows the other example of the conventional wafer support member.

Explanation of symbols

101, 201, 401, 501: Wafer support members 102, 202, 402, 502: Plate-like ceramic bodies 103, 203, 403: Mounting surfaces 104, 204, 404, 504: Electrostatic chucking electrodes 107, 207, 407, 507: base member

Claims (7)

One main surface of the plate-shaped ceramic body is a mounting surface on which a wafer is placed, and an electrostatic chuck portion having electrodes on the other main surface or inside, and a base portion bonded to the electrostatic chuck portion via an adhesive layer A wafer support member comprising: a recess formed in a peripheral portion of the adhesive layer, and an annular protective member disposed in the recess so as to press the wall surface. 2. The wafer support according to claim 1, wherein an outer side of the annular protective member is the same as or inward of an outer side of the electrostatic chuck portion when viewed from a projection plane parallel to the mounting surface. Element. 3. The wafer support member according to claim 1, wherein an opening thickness of the annular protection member is 1.02 to 2.0 times a width of the concave portion. The wafer support member according to any one of claims 1 to 3, wherein the annular protective member is mainly composed of at least one of a fluorine-based resin or a Teflon (registered trademark) -based resin. The wafer supporting member according to claim 1, wherein a heat generating part having a built-in resistance heat generating element is connected between the electrostatic chuck part and the base part via two adhesive layers. . 6. The wafer support member according to claim 5, wherein an end surface around the resistance heating element and the two adhesive layers is a part of a bottom surface of the recess. The wafer supporting member according to claim 1, wherein the recess has a trapezoidal cross section.

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