Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Making electrical device
Reexamination Certificate
1999-06-03
2001-10-30
Duda, Kathleen (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Making electrical device
C430S316000, C430S317000
Reexamination Certificate
active
06309801
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method of manufacturing an electronic device comprising two layers of organic-containing material, said method comprising the steps of:
applying a first layer of organic-containing material to a substrate,
covering the first layer of organic-containing material with a first layer of inorganic material,
applying a second layer of inorganic material which is different from the inorganic material of the first layer,
providing a first mask layer of resist having first openings,
etching through the second layer of inorganic material at the location of the first openings,
etching through the first layer of inorganic material at the location of the first openings,
applying a second layer of organic-containing material,
covering the second layer of organic-containing material with a third layer of inorganic material,
applying a fourth layer of inorganic material which is different from the inorganic material of the third layer,
providing a second mask layer of resist having second openings,
etching through the fourth layer of inorganic material at the location of the second openings,
etching through the third layer of inorganic material at the location of the second openings,
etching through the second layer of organic-containing material at the location of the second openings.
Such a method is known from EP-A-0 680 085. In one embodiment of the known method, an electrical connection is made between conductors on three metallisation levels in a semiconductor device, the connection being made through two layers of organic-containing dielectric material, each separating two adjacent metallisation levels. A first conductive layer is deposited on an insulating layer and subsequently patterned, whereby conductors on a first metallisation level are formed. Then an inorganic substrate encapsulation layer is deposited conformally on the exposed surfaces of the insulating layer and the conductors on the first metallisation level. Subsequently a first layer of organic-containing dielectric material, for example parylene, is deposited on and between the conductors on the first metallisation level. The first layer of organic-containing dielectric material is provided with an inorganic cap layer, for example silicon oxide, which in turn is covered with an inorganic hard mask layer, for example silicon nitride. After providing a mask layer of resist having openings, a via is etched through the inorganic hard mask layer, the inorganic cap layer and the first layer of organic-containing dielectric material at the location of the openings. Subsequently, an inorganic via passivation layer is applied to cover the exposed surfaces of the inorganic substrate encapsulation layer, the first layer of organic-containing dielectric material, the inorganic cap layer and the inorganic hard mask layer. In order to contact the underlying conductor on the first metallisation level, the inorganic via passivation layer is removed from the bottom of the via by anisotropic etching. During this step, the inorganic via passivation layer is removed from the top of the inorganic hard mask layer as well. The inorganic hard mask layer is applied in order to prevent etching of the inorganic cap layer during anisotropic etching. Next, a second conductive layer is applied to fill the via so as to form an electrical connection with the conductor on the first metallisation level at the bottom of the via. The part of the second conductive layer overlying the via is subsequently patterned, thereby forming conductors on a second metallisation level. Starting with the conformal deposition of a further inorganic substrate encapsulation layer and the application of a second layer of organic-containing dielectric material, the sequence of the above process steps is repeated once in order to finally end up with an electrical connection between the conductor on the first metallisation level, the conductor on the second metallisation level and a conductor on a third metallisation level, the connection being made through the first and the second layer of organic-containing dielectric material by means of vias filled with the conductive material.
A disadvantage of the known method is that it is difficult to control the dimensions of the vias.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method of manufacturing an electronic device comprising two layers of organic-containing material, which enables a structure with well-defined dimensions to be made in the layers of organic-containing material.
For this purpose, according to the invention, the method mentioned in the opening paragraph is characterized in that
the second layer of inorganic material is etched in an etch process wherein the second inorganic material is selectively etched with respect to the first inorganic material,
the first mask layer of resist is removed between etching through the second layer of inorganic material and etching through the first layer of inorganic material,
the fourth layer of inorganic material is etched in an etch process wherein the fourth inorganic material is selectively etched with respect to the third inorganic material,
the second mask layer of resist is removed between etching through the fourth layer of inorganic material and etching through the third layer of inorganic material,
etching through the second layer of organic-containing material at the location of the second openings and etching through the first layer of organic-containing material at the location of the first openings take place simultaneously.
A resist mainly contains organic material and it has been found that etch processes for removing resist also etch away organic-containing materials. In each of the two sequences of process steps mentioned in the above described embodiment of the known method, a mask layer of resist is applied for defining the location of the via. During the removal of the mask layer of resist, the layer of organic-containing material to which the via is finally transferred is exposed. Hence, the resist and the organic-containing material are etched at the same time. During this etch process, a transition occurs from etching resist to etching no resist when the resist has been completely removed. This transition causes a considerable change of the etch conditions, thereby adversely affecting the critical dimension control of the etch process. In the method according to the invention, which also includes two sequences of process steps, etching of the first layer of organic-containing material is postponed until the second layer of organic-containing material is etched. In each sequence of process steps, a layer of organic-containing materials applied and this layer is provided with a bottom layer of inorganic material, which in turn is covered with a top layer of inorganic material and a mask layer of resist. By using the method according to the invention the layer of organic-containing material is not exposed during the removal of the mask layer of resist. Because the top layer of inorganic material is etched in an etch process wherein the top inorganic material is selectively etched with respect to the bottom inorganic material, the bottom layer of inorganic material is kept in place without the timing of the etch process for the top layer of inorganic material being critical. Consequently, the mask layer of resist is removed without affecting the layer of organic-containing material. After the removal of the mask layer of resist, the bottom layer of inorganic material is etched by using the top layer of inorganic material as a mask. Finally, after passing through both sequences of process steps, the second and the first layer of organic-containing material are etched in one step. During this last etch step, no transition from etching resist to etching no resist occurs. In comparison with the known method, the method in accordance with the invention therefore results in better defined dimensions of the structure etched in the first and the second layer of organic-containing mater
Manders Bartholome S.
Meijer Petrus M.
Biren Steven R.
Duda Kathleen
U.S. Philips Corporation
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