Semiconductor device manufacturing: process – Chemical etching – Combined with coating step
Patent
1998-02-04
2000-02-29
Bowers, Charles
Semiconductor device manufacturing: process
Chemical etching
Combined with coating step
438703, H01L 2144
Patent
active
060309008
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method for the production of a spacer layer in a structure.
BACKGROUND OF THE INVENTION
Spacer layers, so-called spacers, have acquired great importance in semiconductor technology.
Spacers are produced, for example, in a structure, for example a hole or a trench, in order to bring about lateral electrical insulation of holes, passages or trenches, to deposit so-called seed layers or to incorporate diffusion barriers.
Silicon dioxide (SiO.sub.2) is typically used as the material for the production of an insulating spacer.
A conventional method for the production of an SiO.sub.2 spacer is described below with reference to FIG. 1.
FIG. 1 illustrates a structure 100, which in this cause may be a trench, for example, prior to the deposition of the material forming the spacer. In the example shown in FIG. 1a, the structure 100 is formed in a multilayer structure comprising a first layer 102 and a second layer 104.
The first layer 102 is typically a silicon substrate with transistors (front end), and the second layer 104 is used for the interconnection (metallization) of the transistors (back end), the second layer 104 being composed of SiO.sub.2 into which metal tracks are embedded.
After the formation of the structure 100, SiO.sub.2 is deposited, thereby forming an SiO.sub.2 layer 106 on the surface of the layer 104, on the side walls of the structure 100 and on the bottom of the structure 100, as is shown in FIG. 1b.
The spacer is completed by carrying out anisotropic plasma etching, by means of which the bottom 108 of the structure 100 is exposed, as can be seen in FIG. 1c.
At the same time, the SiO.sub.2 layer 106 above the layer 104 and a small part of the layer 104 are removed by the plasma etching, since the etching rate on the surface of the water is greater than on the bottom of the structure, as can likewise be gathered from FIG. 1c.
It is evident from the above description of the method known from the prior art that this known method for the production of a spacer in a structure encompasses a complicated sequence of steps, comprising the steps of producing the structure, depositing the material from which the spacer is to be produced, and the step of exposing the bottom of the structure by an etching process, the different etching rates on the surface of the water and on the bottom of the structure becoming increasingly problematic in the context of present-day structures which are becoming ever deeper.
Reference is made to the fact that the above-described conventional method from the prior is not suitable solely for removing an SiO.sub.2 layer from a bottom 108 of a structure 100, rather SiO.sub.2 layers are generally removed from horizontal regions in this way.
SUMMARY OF THE INVENTION
Taking the prior art described above as a starting point, the present invention is based on the object of providing a simplified method for the production of a spacer layer in a structure.
The present invention provides a method for the production of a spacer layer in a structure having the following steps: the structure; at a pressure of p=0.2-1 bar and a temperature of 200.degree. C. to 400.degree. C.
The present invention is based on the insight that the anisotropic dry etching for producing the structure brings about the occurrence of instances of damage, modification and/or contamination or implantation primarily on the bottom of a structure. The duration of a following wet etching step for cleaning etching residues from all of the surfaces, typically by means of 1-3% strength hydrofluoric acid (HF), must be chosen to be short enough for the side walls of the structure to be cleaned, but not for the modification of the structure bottom to be completely removed. Suitable process control during the subsequent conformal deposition of the layer forming the spacer has the effect that deposition on the bottom of the structure does not happen, with the result that only the desired lateral spacer is produced by the deposition process. As additional etchin
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Engelhardt Manfred
Grassl Thomas
Bowers Charles
Siemens Aktiengesellschaft
Sulsky Martin
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