DE2654083A1 - PLASMA ETCHING - Google Patents

Description

SIEMENS AKTIENGESELLSCHAFT Our mark

Berlin and Munich VPA 7g ρ 7 15 6 FRG

Plasma etching process

The invention relates to a plasma etching process as specified in the preamble of claim 1.

Plasma etching processes and plasma stripping are used in semiconductor technology increasingly used instead of chemical etching in photolithographic etching processes. In the plasma etching process, a plasma discharge that burns in a quartz reactor is used to remove the substrate Material removed. Plasma stripping is a plasma etching process in which photoresists are removed from a substrate surface in a plasma discharge. In order to avoid radiation damage, it is known that the light plasma zone of the etch material shield with a perforated metal shield ("etching tunnel").

Because the etching rate during plasma etching depends on the local temperature

depends on the substrate surface, must when performing the. Plasma etching process ensures that the substrate temperature is constant and evenly distributed over the substrate surface.

In the plasma etching systems usually used in semiconductor technology, the The temperature of the substrates can only be kept constant by preheating the substrates in an inert gas plasma and that the substrate temperature reached in the process

11/24/1976 /

ORIGINAL. IMSPECTED

following plasma etching process is kept constant by controlling the electrical power exciting the plasma. On the other hand, a change in the electrical power in the plasma discharge represents a change in the etching medium Furthermore, in the case of longer plasma etching times, the "tunnel" insert located in the plasma etching systems has a too low heat capacity, so that even after the substrates have been preheated in an inert gas plasma, there is a further rise in temperature must be accepted. The "etching tunnels" supplied by the device manufacturers thus bring about the temperature constancy does not achieve the improvement indicated for it, at best with very short treatment times. In principle, there is a temperature difference between the start and end temperature. The difference is after preheating lower, for short work, especially when using heat-storing parts, it can possibly be neglected.

The object of the invention is to provide a means with which the temperature of the substrates to be etched in a plasma etching system can be controlled and kept constant.

This task is as in the preamble of the claim 1 specified plasma etching process according to the invention according to the specified in the characterizing part of claim 1 Way solved.

Preferred embodiments of the invention emerge from the subclaims.

According to the invention it is provided that in the plasma etching process a substrate carrier plate is used which can be heated and / or cooled. If this substrate carrier plate is provided with a pipeline according to a particular embodiment of the invention, a temperature-controlled liquid can be pumped through this pipeline and in this way the substrate holder and thus also the substrates can be kept at a constant temperature. A carrier plate is preferably used, the material of which with the

_8 09822/0376
ORIGINAL INSPECTED

.; , 76 P 7 1 56 FRG

Material of the etching tunnel is identical. As a result, uniform conditions are achieved in the plasma etching process, as a result of which the reproducibility of the plasma etching is improved.
5

In the following it is described and explained in more detail with reference to the figure, how the method according to the invention is carried out.

The etching tunnel 3, which consists for example of a cylindrical aluminum tube with perforated walls, is located in an evacuable vessel 1 which can be pumped out via a vacuum line. The vessel 1 is further provided with a gas inlet 4 through which the gas which is used in the plasma etching is admitted. The substrate carrier plate 5 on which the substrates 6 are placed is located in the etching tunnel. A pipe 1 runs in the substrate carrier plate 5. This pipe 7 is passed through the front plate 8 to which the substrate carrier plate 5 is attached, so that a liquid coolant or heating medium can flow through this pipe 7 from the outside. The substrate carrier plate 5 rests on sealing rings so that the vessel 1 is tightly closed. The reaction vessel 1 is pumped out and is then filled with the etchant, for example with Freon, to a pressure of 0.5 to 1 Torr. A Freon inflow of about 50 ml / minute is made possible through the gas inlet 4. This influx of fresh freon is compensated for by simultaneously pumping out the reactor through the vacuum line 2. During the plasma etching of the substrate 6, a coolant is pumped through the substrate carrier plate 5 so that the amount of heat generated during plasma etching of the substrates is dissipated through the substrates into the carrier plate and from there into the coolant.

3 claims
1 figure

809822/0376

Claims (2)

Λ 76 P 7 156 8RD Claims χ i). Plasma etching process in which material is removed from a substrate which is located on a substrate carrier plate in a plasma discharge, and in which the substrate temperature is regulated, characterized in that the substrate temperature is regulated by means of a coolable and / or heatable substrate carrier plate (5) takes place, with which the substrates (6) are in thermal contact, '——' 2. Plasma etching method according to claim 1, characterized in that g e k e η η ζ e i c h η e t that a substrate carrier plate (5) provided with a pipe (7) is used. 3 * plasma etching process according to claim 1 or 2, characterized in that g e that a substrate carrier plate (5) is used, which consists of the same material as a surrounding etching tunnel (3). «09822 / 037.6