JP2003249544A - Electrostatic chuck and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic chuck hardly generating particles due to the friction with a chucked object, such as a silicon wafer. <P>SOLUTION: A mask is applied on the surface of an insulating layer 4, composed mainly of PBN (pyrolytic boron nitride) or C-PBN (carbon-doped PBN). By dry-etching the non-masked surface region of the insulating layer with a plasma-excited etching gas in a vacuum chamber, a mesh-shaped continuous protruded part 7 is formed, and thereafter the mask is removed. For dry etching, a combination of chemical etching by oxygen gas and physical etching by inert gas, such as argon, is preferable. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silicon semiconductor,
The present invention relates to an electrostatic chuck preferably used in a manufacturing process of a compound semiconductor, an FPD (flat panel display), a hard disk, a saw filter, an optical memory device, and other electronic devices, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Silicon semiconductors, compound semiconductors, FPs
In the manufacturing process of D, hard disk, saw filter, optical memory device and other electronic devices, dry etching, PVD (physical vapor deposition),
An electrostatic chuck is widely used to fix an object (silicon wafer, glass base material, aluminum base material, polymer material, etc.) when performing CVD (chemical vapor deposition) or the like.

In an electrostatic chuck, for example, as shown in FIG. 1, a conductor electrode 3 is formed in a predetermined pattern on an insulating base material formed by covering a graphite plate 1 with an insulating layer 2 such as PBN (pyrolytic boron nitride). And the insulating layer 4 covers them. Although not shown, both ends of the electrode 3 are connected to a power source through terminals.

In the electrostatic chuck 6 having this structure, when an object to be attracted 5 such as a silicon wafer is placed on the chuck surface and a voltage is applied between the electrode terminals, a Coulomb force is generated and the object to be attracted 5 is chucked. be able to. Further, in this configuration, the electrostatic chuck also serves as a heater, so that the attracted object 5 is uniformly heated or cooled to an optimum temperature at which an appropriate chuck suction force is exerted.

FIG. 1 shows an example of the construction of a bipolar electrostatic chuck. In the monopolar electrostatic chuck, a single conductor electrode is arranged on an insulating base material and covered with an insulating layer. With the above configuration, a voltage is applied between the electrode and the object to be adsorbed placed on the surface to chuck the object to be adsorbed.

When an object to be attracted is placed or adsorbed on the heated electrostatic chuck, thermal expansion causes rubbing between the object to be attracted and the surface of the electrostatic chuck, which causes electrostatic chucking. It has been pointed out that a part of the surface material of (1) is scraped off, and the scraped substance (hereinafter referred to as particles) adheres to the back surface of the object to be adsorbed and contaminates the inside of the chamber during transportation. Further, if the exposure process proceeds in a state where the particles are still attached to the back surface of the object to be adsorbed, the exposure focus is deviated, and the circuit pattern cannot be printed with high accuracy. In order to avoid such a problem, φ0.2μ on the back surface of an 8-inch wafer
The number of particles of m or more is set to 2000 or less, but when PBN or C-PBN in which carbon is doped is used as the insulating layer, about 40,000 particles are generated.

As a means for reducing the generation of such particles, in an electrostatic chuck using a material such as alumina, aluminum nitride, silicon nitride, etc., which can be processed with high precision by machining, as an insulating layer on the surface, the surface is embossed. Many fine convex parts (texture pattern, dimples,
It is also possible to minimize the contact area with the adsorbed part by making the minute convex parts support the adsorbed part by scattering several% (also called mesas etc.) on the entire surface. Proposed (JP-A-10-335439, JP-A-2000-106392, JP-A-2000-27759)
4, JP 2001-144167 A, Special Table 2001-51
7872).

[0008]

However, according to the conventional technique as described above, since the projections on the surface of the electrostatic chuck formed by the embossing process are individually scattered, the projections are formed. It may be chipped due to friction with the object to be adsorbed, which may rather promote the generation of particles. In particular, in an electrostatic chuck using PBN or C-PBN having a layered structure as an insulating layer on the surface, the above-mentioned conventional technique is applied because the protrusions due to embossing tend to be delaminated due to the friction of the attracted object. It was difficult to do.

[0009]

Therefore, according to the present invention, even in an electrostatic chuck using PBN or C-PBN having a layer structure as a coating layer, generation of particles due to rubbing with an object to be attracted is minimized. The purpose is to provide a possible new configuration.

In order to solve this object, the present invention according to claim 1 provides one or a plurality of conductor electrodes in an insulating layer mainly composed of PBN (pyrolytic boron nitride) or C-PBN in which carbon is doped. The surface of the insulating layer is formed on the surface of the insulating layer, and the electrostatic chuck is configured to attract and fix the object to be attracted to the surface of the insulating layer by energizing the conductor electrode while the object is placed on the surface of the insulating layer. Has a mesh-shaped continuous convex portion, and the surface of the convex portion supports the object to be adsorbed.

According to a second aspect of the present invention, in the electrostatic chuck according to the first aspect, the height of the mesh-shaped continuous convex portions is 5 to 25 μm. If the height of the protrusions is less than 5 μm, the thermally expanded silicon wafer or other adsorbent is bent and comes into contact with the surface of the insulating layer between the protrusions, increasing the contact area and sufficiently suppressing the generation of particles. If the height of the convex portion exceeds 25 μm, it becomes difficult to maintain the Johnson-Rahbek effect, which governs the chucking / dechucking property, and the basic performance of the electrostatic chuck deteriorates.

Another object of the present invention is to provide a method suitable for manufacturing the electrostatic chuck having the above-mentioned structure.

In order to solve this object, the present invention according to claim 3 manufactures an electrostatic chuck in which one or more conductor electrodes are formed in an insulating layer containing PBN (pyrolytic boron nitride) as a main material. After that, a mask patterned in a mesh shape is applied according to the position of the continuous convex portion on the surface of the insulating layer, and the non-mask area on the surface of the insulating layer is dry-etched by the etching gas plasmatized in the vacuum chamber to perform the insulation. This is a method for manufacturing an electrostatic chuck, characterized in that the mask is removed after forming continuous mesh-shaped convex portions on the layer surface. Here, the mesh-shaped continuous protrusions formed on the surface of the insulating layer may be, for example, a form in which the protrusions are continuous in a lattice pattern or a honeycomb pattern.

According to a fourth aspect of the present invention, in the method for manufacturing an electrostatic chuck according to the third aspect, the dry etching is an inert gas containing an element having a molecular weight equal to or higher than boron and nitrogen as an etching gas. Is used to collide with the surface of the insulating layer to sputter boron atoms and nitrogen atoms in the unmasked region.

According to a fifth aspect of the present invention, in the method of manufacturing an electrostatic chuck according to the third aspect, the dry etching uses oxygen as an etching gas to convert boron atoms in a non-masked region on the surface of the insulating layer into B2O3. A chemical etching step of breaking the B—N interatomic bond by oxidation, and an inert gas containing an element having a molecular weight equal to or higher than boron and nitrogen as an etching gas are used to collide with the surface of the insulating layer. And a physical etching step of sputtering B2O3 and nitrogen atoms in the mask area.

According to a sixth aspect of the present invention, in the method of manufacturing an electrostatic chuck according to the fourth or fifth aspect, the inert gas containing an element having a molecular weight equal to or higher than boron and nitrogen is argon or nitrogen. , One gas selected from the group consisting of neon, krypton, and xenon, or a mixed gas thereof.

The present invention according to claim 7 provides C-PBN obtained by doping carbon into PBN (pyrolytic boron nitride).
After manufacturing an electrostatic chuck in which one or more conductor electrodes are formed on an insulating layer containing as a main material, a mask patterned in a mesh shape is applied according to the position of continuous convex portions on the surface of the insulating layer, and a vacuum chamber A method of manufacturing an electrostatic chuck, characterized in that a mesh-shaped continuous convex portion is formed on the surface of the insulating layer by dry-etching a non-masked area on the surface of the insulating layer with plasma of an etching gas.

According to an eighth aspect of the present invention, in the method of manufacturing an electrostatic chuck according to the seventh aspect, the dry etching includes an etching gas containing boron, nitrogen, and an element having a molecular weight equal to or higher than that of carbon. It is characterized in that it includes a physical etching step of sputtering boron atoms, nitrogen atoms and carbon atoms in the non-masked region by colliding with the surface of the insulating layer using an active gas.

According to a ninth aspect of the present invention, in the method of manufacturing an electrostatic chuck according to the seventh aspect, the dry etching uses oxygen as an etching gas to remove carbon atoms in the non-masked region of the insulating layer from CO and CO. / Or C
A chemical etching step of oxidizing the boron atoms to B2O3 by oxidizing them to the outside of the system by oxidizing them to O2, and a molecular weight equal to or higher than that of boron, nitrogen and carbon as an etching gas. And a physical etching step of sputtering B2O3 and nitrogen atoms in the non-masked region by colliding with the surface of the insulating layer using an inert gas containing the element.

The present invention according to claim 10 provides the method of manufacturing an electrostatic chuck according to claim 8 or 9, wherein the inert gas containing boron, nitrogen and an element having a molecular weight equal to or higher than carbon is argon. , Nitrogen, neon,
It is characterized by being one gas selected from the group consisting of krypton and xenon or a mixed gas thereof.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Graphite plate 1 having a thickness of 10 mm
A PBN insulating layer 2 having a thickness of 300 μm is formed on the surface of the substrate by the CVD method, and PG having a thickness of 50 μm is also formed by the CVD method.
After forming layers on both sides, the conductor electrode 3 of this PG layer
The conductor electrode 3 having a predetermined pattern was formed on both surfaces of the PBN insulating layer 2 by removing the other portion, leaving the predetermined pattern portion. Then, 3 moles of ammonia and 2.4 moles of methane gas are reacted with 1 mole of boron trichloride by a CVD method at 0.5 Torr and a temperature of 1850 ° C., and 100 μm thick carbon-added PBN (C-
The PBN insulating layer 4 was formed to obtain the bipolar electrostatic chuck 6 having the structure shown in FIG. This electrostatic chuck 6
When the electric resistivity of the C-PBN coating layer 4 in was measured, it was 2.8 × 10 12 Ω · cm.

On the surface of the C-PBN insulating layer 4 of the obtained electrostatic chuck 6, convex portions 7 continuous in a lattice pattern as shown in FIG.
In order to form the film, a plasma dry etching process was performed using the apparatus having the configuration shown in FIG. That is, the surface of the insulating layer 4 of the electrostatic chuck 6 is provided with a mask patterned in a lattice shape according to the formation position of the convex portion 7, and is placed on the electrode 11 in the plasma chamber 10, and the vacuum pump 12 Thus, the inside of the chamber 10 is adjusted and maintained at a predetermined degree of vacuum, an etching gas is introduced from the gas introduction unit 17, and a high frequency is applied to the electrostatic chuck 6 from the high frequency RF power source 13 via the mixing unit 16. As a result, the plasma region 14 is formed around the electrostatic chuck 6, and the introduced etching gas is ionized. Then, after a lapse of a predetermined afterglow time (time from the application of the high frequency voltage for plasma formation to the application of the pulse voltage), the pulse power supply 15
By applying a predetermined pulse voltage to the electrostatic chuck 6 through the mixing unit 16, the ions of the etching gas are moved at high speed to collide with the non-masked area on the surface of the insulating layer 4.

In the first embodiment, argon is used as an etching gas, and the plasma region 14 of the vacuum chamber 10 is used.
By bombarding the surface of the insulating layer 4 of the electrostatic chuck 6 with the ionized argon, the B
(Boron atoms), N (nitrogen atoms) and C (carbon atoms) are physically sputtered away. The etching in the first embodiment is called physical etching or sputter etching performed by the mechanism shown in FIG.

In the second embodiment, a two-step dry etching process is performed. In the first step, oxygen is used as an etching gas, and the oxygen plasma formed in the plasma region 14 of the vacuum chamber 10 is caused to collide with the surface of the insulating layer 4 of the electrostatic chuck 6 to thereby remove carbon atoms in the non-masked region of the insulating layer surface. Is oxidized to CO and / or CO2 and discharged to the outside of the system, and the boron atom is oxidized to B2O3 to break the interatomic bond of BN. In the second step, argon is used as an etching gas, and argon ionized in the plasma region 14 of the vacuum chamber 10 is made to collide with the surface of the insulating layer 4 to remove B2O3 and nitrogen atoms existing in the non-masked region by the first step. Physically sputter and remove. The etching in the second embodiment is performed by a mechanism as shown in FIG.
Of these, the first step by (A) to (B) (actually not substantially time-sequentially and substantially simultaneously) is called chemical or reactive etching, plasma etching or excited gas etching, and (D). The second step is referred to as physical etching or sputter etching in the same manner as the reaction mechanism (FIG. 4) according to the first embodiment described above.

In the third embodiment, a two-step dry etching process is performed as in the second embodiment, and is the same as the second embodiment except that nitrogen is used as an etching gas in the second step. . The etching in the third embodiment is performed by the mechanism shown in FIG.

By performing the etching process as described above, the non-masked region on the surface of the insulating layer 4 in the electrostatic chuck 6 is etched, and the convex portions 7 (FIG. 3) which are continuous in a mesh shape on the surface of the insulating layer. Is formed, the mask is removed thereafter to manufacture the electrostatic chuck of the present invention. For masking and mask removal, it is possible to employ a method in which the photoresist thin film is partially exposed and removed to perform masking, and after etching, the photoresist mask is removed using an asher or the like. it can.

The etching treatment in the above-mentioned first to third embodiments is carried out under the conditions shown in FIG. 7, and the mesh-shaped continuous convex portions 7 having a width of 0.1 mm at intervals of 3 mm are formed on the surface of the insulating layer 4. The total surface area of the parts is about 6% of the total surface area of the insulating layer 4), an electrostatic chuck is manufactured, and an 8-inch wafer is placed on the mesh-shaped continuous convex parts 7 and heated and adsorbed. The number of generated particles of φ0.2 μm or more on the back surface was about 2400 in all, and the number of generated particles when using a conventional electrostatic chuck in which the surface of the insulating layer 4 made of PBN or C-PBN was smoothed ( It was possible to reduce to about 6% (about 40,000).

The present invention is not limited to the above embodiment, and various embodiments can be taken within the scope of the invention described in each claim of the claims. Speaking of the etching gas, the etching gas in the first embodiment collides with the surface of the insulating layer to sputter boron atoms, nitrogen atoms and carbon atoms in the non-masked area to perform physical etching. And an inert gas containing an element having a molecular weight equal to or higher than that of nitrogen can be used.
Neon (Ne), Krypton (Kr), Xenon (X
e) and the like can be used alone or in an arbitrary mixture.
Since the etching gas used in the second step in the second and third embodiments also collides with the surface of the insulating layer to sputter boron atoms, nitrogen atoms and carbon atoms in the non-masked region to perform physical etching. In addition to the above-mentioned argon (second embodiment) and nitrogen (third embodiment), neon (Ne), krypton (Kr), xenon (Xe) and the like can be used alone or in an arbitrary mixture.

[0029]

According to the electrostatic chuck of the present invention, the PBN
Alternatively, since the surface of the C-PBN insulating layer has a mesh-shaped continuous convex portion and the surface of the convex portion is configured to support an adsorbed object such as a silicon wafer, The contact area is minimized, and it is possible to suppress the generation of particles due to rubbing with the object to be adsorbed.

The protrusions on the surface of the insulating layer are not discretely scattered like the protrusions formed by the conventional embossing process, but the protrusions are continuous in a mesh shape. Since the continuous convex portions of (1) exhibit strength against peeling, peeling due to rubbing with the object to be adsorbed is unlikely to occur even in an insulating layer having a layered structure of which main component is PBN or C-PBN.

Further, by adopting the dry etching process using a specific etching gas, an electrostatic chuck having a mesh-shaped continuous convex portion on the surface of the insulating layer can be efficiently manufactured.

[Brief description of drawings]

FIG. 1 is a structural diagram of a bipolar electrostatic chuck.

FIG. 2 is a schematic diagram showing an example of an apparatus configuration for an etching process performed to form a mesh-shaped continuous convex portion on the surface of an insulating layer in the method of manufacturing an electrostatic chuck according to the present invention.

FIG. 3 is a schematic perspective view showing a mesh-shaped continuous convex portion on the surface of the insulating layer of the electrostatic chuck of the present invention.

FIG. 4 is an explanatory diagram showing an embodiment of an etching process performed to form mesh-shaped continuous protrusions on the surface of an insulating layer in the method of manufacturing an electrostatic chuck according to the present invention.

FIG. 5 is an explanatory view showing another embodiment of an etching process performed to form a mesh-shaped continuous convex portion on the surface of an insulating layer in the method for manufacturing an electrostatic chuck according to the present invention.

FIG. 6 is an explanatory view showing still another embodiment of the etching treatment performed for forming the mesh-shaped continuous convex portions on the surface of the insulating layer in the method for manufacturing the electrostatic chuck according to the present invention.

FIG. 7 is a table illustrating the conditions of the etching process according to each of the embodiments shown in FIGS.

[Explanation of symbols]

1 Graphite plate 2 insulating layers 3 conductor electrode 4 insulating layers 5 Objects to be adsorbed such as silicon wafers 6 electrostatic chuck 7 Mesh-shaped continuous protrusions 10 Plasma chamber 11 electrodes 12 Vacuum pump 13 RF power supply 14 Plasma region 15 pulse power supply 16 mixing units 17 Gas introduction section

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyotoshi Fujii             580-Furusenouchi, Kuzaki, Kamitsuki-cho, Sayo-gun, Hyogo Prefecture             39 Advance Ceramics Inter             National Corporation Kozuki Factory F-term (reference) 4K029 AA06 AA24 JA05                 4K030 CA04 CA12 GA01 KA47                 5F004 AA13 BA09 BB22 BB29 BD04                 5F031 CA01 CA02 CA05 HA03 HA08                       HA17 HA18 MA27 MA28 MA29                       MA32 NA05 PA26                 5F045 AA08 BB15 DP03 DQ10 EB03                       EH13 EM05 EM09

Claims (10)

[Claims] 1. One or more conductor electrodes are formed on an insulating layer mainly composed of PBN (pyrolytic boron nitride) or carbon-doped C-PBN, and an object to be adsorbed is placed on the surface of the insulating layer. In an electrostatic chuck configured to attract and fix an object to be attracted to the surface of the insulating layer by energizing the conductor electrode in a placed state, the surface of the insulating layer has a mesh-shaped continuous convex portion, An electrostatic chuck characterized in that an object to be attracted is supported on the surface of the convex portion. 2. The height of the mesh-like continuous convex portions is 5 to 2
The electrostatic chuck according to claim 1, wherein the electrostatic chuck has a thickness of 5 μm. 3. A continuous convex portion position to be formed on the surface of an insulating layer after manufacturing an electrostatic chuck in which one or more conductor electrodes are formed on an insulating layer containing PBN (pyrolytic boron nitride) as a main material. According to the above, a mask patterned in a mesh shape is applied, and a non-masked area of the insulating layer surface is dry-etched by an etching gas plasmatized in a vacuum chamber to form a mesh-shaped continuous convex portion on the insulating layer surface. A method of manufacturing an electrostatic chuck, which comprises removing the mask after the formation. 4. In the dry etching, an inert gas containing an element having a molecular weight equal to or higher than boron and nitrogen is used as an etching gas to collide with the surface of the insulating layer to remove boron atoms and nitrogen atoms in a non-mask region. The method of manufacturing an electrostatic chuck according to claim 3, further comprising a physical etching step of sputtering. 5. The dry etching is a chemical etching step of breaking the BN interatomic bond by oxidizing boron atoms in the non-masked region of the insulating layer surface to B2O3 using oxygen as an etching gas, and etching. And an inert gas containing an element having a molecular weight equal to or higher than that of boron and nitrogen as a gas to collide with the surface of the insulating layer to sputter B2O3 and nitrogen atoms in the unmasked region. The method of manufacturing an electrostatic chuck according to claim 3. 6. The inert gas containing an element having a molecular weight equal to or higher than boron and nitrogen is one gas selected from the group consisting of argon, nitrogen, neon, krypton and xenon or a mixed gas thereof. The method for manufacturing an electrostatic chuck according to claim 4, wherein 7. An electrostatic chuck in which one or more conductor electrodes are formed on an insulating layer mainly composed of C-PBN, which is carbon-doped PBN (pyrolytic boron nitride), and then the surface of the insulating layer is manufactured. A mask patterned in a mesh shape is applied according to the position of the continuous convex portions to be formed on the surface of the insulating layer, and the non-mask area on the surface of the insulating layer is dry-etched by plasma of an etching gas in a vacuum chamber to form a mesh shape on the surface of the insulating layer. A method for manufacturing an electrostatic chuck, characterized in that the mask is removed after forming continuous protrusions on the surface. 8. In the dry etching, an inert gas containing an element having a molecular weight equal to or higher than boron, nitrogen and carbon is used as an etching gas to collide with the surface of the insulating layer, and boron atoms and nitrogen in a non-masked region are used. The method of manufacturing an electrostatic chuck according to claim 7, further comprising a physical etching step of physically sputtering atoms. 9. The dry etching uses oxygen as an etching gas to oxidize carbon atoms in a non-masked region on the surface of the insulating layer into CO and / or CO2 and discharge them out of the system, and oxidize boron atoms into B2O3. The chemical etching step of breaking the interatomic bond of B--N is carried out, and an inert gas containing an element having a molecular weight equal to or higher than boron, nitrogen and carbon is used as an etching gas to collide with the surface of the insulating layer and B2 in the mask area
8. The method for manufacturing an electrostatic chuck according to claim 7, further comprising a physical etching step of sputtering O3 and nitrogen atoms. 10. A gas selected from the group consisting of argon, nitrogen, neon, krypton and xenon or a mixed gas thereof, wherein the inert gas containing an element having a molecular weight equal to or higher than boron, nitrogen and carbon. The method for manufacturing an electrostatic chuck according to claim 8 or 9, wherein