JPS59188135A - Attracting method of semiconductor substrate - Google Patents

Abstract

PURPOSE:To obtain an attracting method of good cooling efficiency which can readily attract a substrate with strong force by placing directly the substrate on a flat electrode, applying a voltage between the electrode and the substrate, and attracting by Johnsen-Rahbeck effect. CONSTITUTION:An airtight treating room 10 has a gas inlet port 11 and a gas exhaust port 12, an exhaust pump 14 is connected through a valve 13 to the port 12, and the interior of the room 10 is reduced under pressure. A substrate 15 to be treated of a silicon wafer is placed on attracting plates (flat electrodes)16, 17 in the room 10. The plates 16, 17 have flat upper surfaces of the same plane, and are formed, for example, in P type silicon semiconductors of a pair strictly isolated therebetween. When a voltage is applied from a power source 18 to the plates 16, 17 which are insulated from each other, the voltage is also applied to between the plates 16, 17 and the substrate 15, and the substrate 15 is attracted to the plates 16, 17 by Johnsen-Rahbeck effect.

Description

[Detailed description of the invention] (b) Technical field of the invention ``Kienori'' relates to a method for adsorbing semiconductor substrates.

(B) Prior Art and Problems In the manufacturing process of semiconductor devices, it is necessary to fix the semiconductor substrate within the processing equipment. Conventionally, a vacuum 79 bonding method has been used, but when processing under reduced pressure, the suction force becomes weaker, so it is the standard method. Therefore, static M1 without such inconvenience
Adsorption methods are also used, but they have the following problems.

In the embodiment of FIG. 1 (A), a semiconductor substrate 3 is placed on an insulating thin film 2 formed on a plane i, tiII!l. Place the electrode l
By applying a voltage between the semiconductor substrate 3 and the semiconductor substrate 3, the substrate 3 is attracted. In the embodiment shown in FIG. 1(b), an insulating thin film 2 is formed on a pair of planar electrodes 4 and 5, a semiconductor substrate 3 is placed on top of the insulating thin film 2, and a voltage is applied between the electrodes 4 and 5. It is absorbed by this. In order to increase the adsorption force in such an electrostatic adsorption method, it is necessary to reduce the thickness of the insulating film or increase the applied voltage. However, these two methods are contradictory. That is, in order to prevent dielectric breakdown, if the insulating film is warped, the applied voltage must be lowered considerably; on the other hand, if the applied voltage is increased, the insulating film must be made thicker. Furthermore, since the insulating film is made of resin, it has poor thermal conductivity, making it difficult to cool the semiconductor substrate. .

e→ Purpose of the Invention In view of the current state of the prior art as described above, it is an object of the present invention to provide a method for easily and strongly adsorbing a semiconductor substrate and also having high efficiency.

The present invention achieves the above object by placing a plate directly on at least one flat surface and connecting the flat box, the pole and the semiconductor. A method for adsorbing a semiconductor substrate is characterized in that a voltage is applied between the substrates and the semiconductor substrate is adsorbed to the flat electrode by a Johnsen-Rapek effect 2.

(e) Embodiments of the invention
The n-Rahbek) effect refers to a development in which when a semiconductor and a metal or a semiconductor and a semiconductor are brought into surface contact and a voltage of about 200 V is applied, an adsorption force acts between them. When a semiconductor is brought into surface contact with a metal semiconductor, microscopically they contact each other at a very small point, which is equivalent to the electrodes of a parallel plate capacitor with a small gap of about 10-' to 1O-7 crn. In this state, an adsorption force is generated. This adsorption force F is expressed by the formula ε=εrε In the formula, ε: dielectric strength of the small gap ■: applied pressure d: size of the small gap S: contact area εr: 1 to lO εo: 8.9X I O"[IC2N'm""2
]. In order to estimate the suction force per unit area, ε,=1. εo”=8.9×10−”[C2N
-'cm''], V=200 [v], d=lO-7
By substituting [m] and S-10-4 [m2], F =
1.78X] 03[N]= 1.74X] O'
It weighs Kg. In reality, about 1% of this adsorption force is generated, but the adsorption force is still large (approximately 100% of that of electrostatic and adsorption).
times). Moreover, since the semiconductor substrate is placed in direct contact with the metal or semiconductor, the cooling efficiency of the semiconductor substrate is improved.

The method of applying a voltage between the semiconductor substrate and the planar electrode is as shown in FIG.
It may be applied from above, but as shown in Figure 2 (b),
It is also possible to place the semiconductor substrate 2 on a pair of planar molds 41i7.8 that are placed on each other, and to apply a voltage between the pair of planar electrodes 7 and 8.

FIG. 3 schematically shows a plasma etching apparatus which is a specific embodiment of the present invention. The airtight processing v]0 has a gas inlet 11 and a gas outlet 12, and an exhaust pump 14 is connected to the gas outlet [2] via a pulp 13, so that the inside of the processing chamber 10 is reduced in pressure. A substrate 15 to be processed, such as a silicon wafer, is placed on a suction plate (plane electrode) in the processing chamber 10.
It is placed on top of 16°17. Adsorption plate (plane electrode)】6
17 are individual pieces of, for example, P-type silicon ten-column bodies, which form a pair having flat upper surfaces that are coplanar and are strictly spaced apart from each other. When a voltage of about 200 to 400 cm is applied from the frost source 18 to the suction plates 16 and 17 which are insulated from each other, a voltage is also applied between each suction plate 16 and the semiconductor substrate 15, resulting in the Johnsen-Rahbek effect. , semiconductor substrate 15
is attracted to the suction plates 16 and 17.

Adsorption plates (plane electrodes) 16 and 17 are supported via insulating plates 19 made of Al, O, and aluminum, and the support 20 is provided with water cooling equipment 1i11. Cooling water enters through the cooling water inlet 22, circulates within the cavity 21 of the support 20, and exits through the cooling water outlet 23. There is an electrode 24 above the adsorption plates 16 and 17, which serves as one electrode for the radio frequency power supplied from the high frequency power source 25. The high-frequency power of the plasma converts the gas introduced into the processing chamber from the gas inlet into plasma, and the plasma gas etches the semiconductor substrate 15. 1. The other components of the plasma etching apparatus are the same as conventional ones.

The adsorption plates 16 and 17 were made of P-type silicon semiconductor in the above embodiments, but they could also be made of conductive rubber, for example, hard silicone rubber containing metal powder (resistance R≦300, about -3).
Since the material made with this material has rubber elasticity, even if dust adheres to the surface of the suction plate, the adhesion between the semi-transparent substrate and the suction plate will not be hindered. Therefore, stable suction force can be obtained and suction errors can be prevented. Furthermore, as shown in FIG. 4, by providing a large number of convex portions each having a diameter of about 1 mm on the suction surface of the conductive rubber, suction errors due to filtration can be more reliably prevented. In addition, in the 4th and 1st, the suction plate, that is, both 'FUiw30 #31, is shown as a semicircle in 2 or 2.
In actual practice, a double helical force and efficient π71-pole #j structure are used, and each of them is well-sized.

(6) Effect of Departure J] As is clear from the above explanation, the present invention enables
4A; By simply applying pressure between the substrate and the electrode 111, strong adsorption of the semiconductor substrate can be achieved without providing an insulating film therebetween. Therefore, there is no need to worry about dielectric breakdown, and it is possible to construct a prefectural office building that is strong and has good thermal conductivity. The structure of the device is simple and easy to manufacture. Furthermore, it is also possible to prevent suction errors due to dirt adhering.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view explaining the electrostatic adsorption method, FIG. 2 1 is a cross-sectional view explaining the light absorption method using the Johnsen-Rapek effect, and FIG. 3 is a plasma etching device according to an embodiment of the present invention. Shelf, schematic sectional view, FIG. 4 is a perspective view showing one bill of the finger sucking board 1, ], 4, 5, 6, 7, 8... Planar electrode, 2... Insulating film, 3... semiconductor substrate, 10...
Processing chamber, 16.17...Adsorption plate (plane electrode), 18.
... tTt source, 19 ... Extinction body, 24 ... Electrode, 2
5... High frequency power supply, 30.31... Adsorption plate. Patent applicant: Fujitsu Limited Patent attorney: Akira Aomizu 1: Attorney: Kazuyuki Nishidate Patent attorney: Teio Uchida Patent attorney: Akira Yamaguchi
B) Thread 2'=+ (A) (
b) Figure 3 Ji 41 drops)

Claims (1)

[Claims] 1 Place a semiconductor substrate directly on at least one flat electrode, apply a voltage between the flat electrode and the semiconductor substrate, and place the semiconductor substrate on the flat electrode by the Johnsen-Rahbek effect. A method for adsorbing a semiconductor substrate, which is characterized in that it adsorbs to a semiconductor substrate.