Patent Application
20140079087
1. Field
The present disclosure relates to laser diode fabrication and, more generally, to photolithographic techniques in semiconductor processing.
2. Technical Background
Fabrication processes for laser diodes and other semiconductor devices commonly employ photolithographic techniques and related processing steps. These photolithographic techniques can be relatively complex.
Methods of fabricating laser diodes and other semiconductor structures are provided where lift-off processing is utilized to leave a patterned isolation region of an insulating layer in residence over the axially extending waveguide structure of the laser diode. Resulting semiconductor structures of novel configuration are also contemplated.
In accordance with one embodiment of the present disclosure, a method of fabricating a laser diode structure is provided where a photolithographic process is utilized to form at least a portion of an axially extending waveguide structure such that a patterned photoresist remnant resides over the axially extending waveguide structure following the photolithographic process. A patterned isolated opening and a lift-off photoresist portion are formed in the patterned photoresist remnant by subjecting the patterned photoresist remnant to an additional photolithographic process such that the lift-off photoresist portion remains in residence over the axially extending waveguide structure following the additional photolithographic process. An insulating layer is formed over the patterned isolated opening and the lift-off photoresist portion. The insulating layer and the underlying lift-off photoresist portion are subject to a lift-off process to leave a patterned isolation region of the insulating layer in residence over the axially extending waveguide structure. Additional embodiments are contemplated where the concepts of the present disclosure are applied more generally to laser diode structures and photolithographic techniques in semiconductor processing.
The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:
Methods of fabricating laser diode and other semiconductor structures in accordance with the teachings of the present disclosure can be conveniently illustrated with reference to the laser diode structure 100 of
The initial steps of a photolithographic process according to the present disclosure can be illustrated with reference to
Similarly, it is noted that the laser diode structure 100 in general and the waveguide structure 20 in particular are not described or illustrated in detail herein because these structures can take a variety of conventional and yet to be developed forms, only one of which is illustrated schematically in
Referring collectively to
Referring to
Additional insulating layer compositions are contemplated including, for example, silicon oxide, e.g., SiO2, TiO2 and ZrO2. Beyond this, it is noted that the particulars of conventional and yet-to-be developed semiconductor lift-off processing are beyond the scope of the present disclosure and can be gleaned from suitable teachings in the art.
Accordingly, referring collectively to
For example, and not by way of limitation, where the laser diode structure 100 comprises a DBR semiconductor laser, the patterned isolation region 42 can be tailored to reside over a wavelength selective DBR portion of the laser. More generally, the limited axial dimension of the waveguide structure 20 may correspond to a wavelength selective portion of the laser diode structure and the control element may be configured to control a wavelength selective characteristic of the wavelength selective portion of the laser diode structure. More generally still, the laser diode structure may comprise a plurality of functional regions and the patterned isolation region may be formed over one of the functional regions of the laser diode structure to isolate electrically the gain section of the laser diode from the control element. Alternatively, the isolation region may be formed near the laser facet as an unpumped window section of the laser diode.
For the purposes of describing and defining the present invention, it is noted that a “semiconductor substrate” denotes any construction comprising a semiconductor material. Examples of semiconductor substrates include semiconductor wafers or other bulk semiconductor materials (either alone or in assemblies comprising other materials), and semiconductor material layers (either alone or in assemblies comprising other materials). It should be further noted that, for the purposes of defining and describing the present invention, reference herein to a layer or material being formed “over” a substrate or another layer or material denotes formation above or in contact with the surface of the underlying substrate or layer and does not preclude the presence of intervening layers.
It is noted that recitations herein of a component of the present disclosure being “configured” in a particular way, to embody a particular property, or function in a particular manner, are structural recitations, as opposed to recitations of intended use. More specifically, the references herein to the manner in which a component is “configured” denotes an existing physical condition of the component and, as such, is to be taken as a definite recitation of the structural characteristics of the component.
It is noted that terms like “preferably,” “commonly,” and “typically,” when utilized herein, are not utilized to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to identify particular aspects of an embodiment of the present disclosure or to emphasize alternative or additional features that may or may not be utilized in a particular embodiment of the present disclosure.
For the purposes of describing and defining the present invention it is noted that the term “substantially” is utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. The term “substantially” is also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue.
Having described the subject matter of the present disclosure in detail and by reference to specific embodiments thereof, it is noted that the various details disclosed herein should not be taken to imply that these details relate to elements that are essential components of the various embodiments described herein, even in cases where a particular element is illustrated in each of the drawings that accompany the present description. Rather, the claims appended hereto should be taken as the sole representation of the breadth of the present disclosure and the corresponding scope of the various inventions described herein. Further, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.
It is noted that one or more of the following claims utilize the term “wherein” as a transitional phrase. For the purposes of defining the present invention, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.”
This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Ser. No. 61/490,753, filed on May 27, 2011, the content of which is relied upon and incorporated herein by reference in its entirety.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2012/038928 | 5/22/2012 | WO | 00 | 11/22/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61490753 | May 2011 | US |
