Device and method for stopping etching process
First Claim
1. A method for etching a layer assembly comprising an intermediate layer sandwiched between an etch layer and a stop layer, the method comprising:
- in a region for forming a via contact to a contact portion of the stop layer, etching the etch layer using a first etchant, the etch layer comprising a first material and the first etchant comprising a first etch selectivity with respect to the etch layer and the intermediate layer; and
etching the intermediate layer using a second etchant, the second etchant comprising a second etch selectivity with respect to the intermediate layer and the stop layer, wherein the second etchant is different from the first etchant, wherein the etch layer has a planar lower surface adjacent the intermediate layer and a non-planar upper surface over the contact portion of the stop layer, and wherein a thickness of the etch layer overlying the contact portion of the stop layer varies more than 10% around a mean value, wherein the etch layer has a variable thickness in the region to be etched for forming the via contact, and wherein the thickness is measured from the planar lower surface to the non-planar upper surface.
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Abstract
A method for etching a layer assembly, the layer assembly including an intermediate layer sandwiched between an etch layer and a stop layer, the method including a step of etching the etch layer using a first etchant and a step of etching the intermediate layer using a second etchant. The first etchant includes a first etch selectivity of at least 5:1 with respect to the etch layer and the intermediate layer. The second etchant includes a second etch selectivity of at least 5:1 with respect to the intermediate layer and the stop layer. The first etchant being is different from the second etchant.
14 Citations
31 Claims
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1. A method for etching a layer assembly comprising an intermediate layer sandwiched between an etch layer and a stop layer, the method comprising:
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in a region for forming a via contact to a contact portion of the stop layer, etching the etch layer using a first etchant, the etch layer comprising a first material and the first etchant comprising a first etch selectivity with respect to the etch layer and the intermediate layer; and etching the intermediate layer using a second etchant, the second etchant comprising a second etch selectivity with respect to the intermediate layer and the stop layer, wherein the second etchant is different from the first etchant, wherein the etch layer has a planar lower surface adjacent the intermediate layer and a non-planar upper surface over the contact portion of the stop layer, and wherein a thickness of the etch layer overlying the contact portion of the stop layer varies more than 10% around a mean value, wherein the etch layer has a variable thickness in the region to be etched for forming the via contact, and wherein the thickness is measured from the planar lower surface to the non-planar upper surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for manufacturing a semiconductor structure, the method comprising:
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forming a stop layer having a third material; forming an intermediate layer over the stop layer, the intermediate layer comprising a second material and having an intermediate layer thickness; forming an etch layer over the intermediate layer, the etch layer comprising a first material and having an etch layer thickness; and performing a first etching step with a first etch selectivity in a region for forming a via contact, the first etching step being performed using a fluorocarbon etchant; wherein a ratio of the etch layer thickness to the intermediate layer thickness is at most 3 times the etch selectivity of the first etching step; wherein the first and second materials are such that the first etch selectivity for the fluorocarbon etchant between the first and second materials is at least a ratio of 5;
1;wherein the second and third materials are such that a second etch selectivity for a fluoro-methane etchant between the second and third materials is at least a ratio of 5;
1;wherein the etch layer comprises an inclusion in a region to be etched for forming a via contact; and wherein the inclusion has an etching rate different than the etching rate of the first material when exposed to the fluorocarbon etchant. - View Dependent Claims (15, 16, 17)
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18. A method of forming a semiconductor structure, the method comprising:
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forming a stop layer of a first material over a semiconductor substrate, the stop layer comprising a contact layer and having a stop layer thickness; forming an intermediate layer of a second material over the stop layer, the intermediate layer having an intermediate layer thickness; and forming an etch layer of a third material over the intermediate layer, the etch layer having an etch layer thickness, forming a via contact in a region by etching the etch layer, the intermediate layer, and the stop layer, wherein, due to non-uniformities in the etch layer, an etching rate through the third material of the etch layer varies across the region to be etched for forming the via contact and wherein the non-uniformities comprise one or more of inclusions, impurities, air bubbles or contamination. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A method of forming a semiconductor structure, the method comprising:
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forming a stop layer of a first material over a semiconductor substrate, the stop layer comprising a conductive layer and having a stop layer thickness; forming an intermediate layer of a second material over the stop layer, the intermediate layer having an intermediate layer thickness; and forming an etch layer of a third material over the intermediate layer, the etch layer having an etch layer thickness, forming a via contact in a region by etching the etch layer, the intermediate layer, and the stop layer; wherein the etch layer comprises an inclusion, wherein the inclusion has an etching rate different than the etching rate of the third material during the etching, and wherein a thickness of the etch layer varies more than 10% around a mean value, wherein the etch layer has a variable thickness in the region to be etched for forming the via contact, and wherein the thickness is measured from a planar lower surface of the etch layer to a non-planar upper surface of the etch layer; and wherein the etch layer comprises a first non-uniformity in a region to be etched for forming the via contact, wherein the first non-uniformity extends substantially through the etch layer thickness, wherein the etch layer further comprises a second non-uniformity in the region to be etched for forming the via contact, wherein the second non-uniformity extends only partially through the etch layer thickness, and wherein sidewalls of the first non-uniformity are non-uniform, and wherein a bottom surface of the first non-uniformity is non-uniform. - View Dependent Claims (29, 30, 31)
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Specification