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US 7,171,975 B2Granted
Fabrication of ultra-shallow channels for microfluidic devices and systems
AssigneeKionix, Inc.
InventorsJames E. Moon, Lincoln C. Young
Life of this patent
Estimating the term…
Abstract
A method for etching an ultra-shallow channel includes using an etch process that is selective for one material to etch a different material in order to achieve a very precise channel depth in the different material. Channels as shallow as 10 nm can be fabricated in silicon with precision of 5 nm or better using the method. Stepped channels can be fabricated where each segment is a different depth, with the segments being between 10 nm and 1000 nm in depth. The method is applied to create a fluidic channel which includes a channel substrate to which is bonded a lid substrate to confine fluids to the fluidic channels so fabricated.
Claims81
A method for etching an ultra-shallow channel, comprising the steps of:
- providing a substrate of a first material;
- forming a layer of a second material on at least part of said first material;
- selectively removing a portion of said second material such that said second material is completely removed in at least one area to expose at least one area of said first material and is at least partially persistent in areas adjacent to said at least one exposed area of said first material so as to provide direct etchant communication with said first material within said at least one exposed area and to prevent etchant communication with said first material in areas where said second material has not been completely removed, and such that said act of removing said portion of said second material does not significantly remove any of said first material;
- providing an etch process that is selective for said second material and selective to said first material, wherein said etch process preferentially etches said second material at a rate that is significantly greater than that at which said etch process would etch said first material;
- and applying said etch process to etch said first material to a desired depth of said ultra-shallow channel.
2 more elements
A method for etching an ultra-shallow channel, comprising the steps of:
- providing a substrate of a first material;
- forming a masking layer of a second material on at least part of said first material;
- coating said masking layer with a photoresist layer;
- defining a pattern in said photoresist layer;
- transferring said pattern into said masking layer using a dry etching process selective for said second material at a first etch rate until said first material is exposed;
- and etching said exposed first material using said dry etching process at a rate less than said first etch rate until a desired depth of said ultra-shallow channel is achieved in said first material.
3 more elements
A method for etching an ultra-shallow channel, comprising the steps of:
- providing a substrate of a first material;
- forming a masking layer of a known depth of a second material on at least part of said first material;
- determining a first etch rate of a dry etching process in said first material where said dry etching process is selective for said second material;
- determining a second etch rate of said dry etching process in said second material;
- coating said masking layer with a photoresist layer;
- defining a pattern in said photoresist layer;
- transferring said pattern into said masking layer using said dry etching process;
- and continuing etching said first material using said dry etching process until a desired depth of said ultra-shallow channel is achieved in said first material, where a total time for etching said first and second materials is determined by dividing said desired depth in said first material by said first etch rate to obtain a first time, dividing said known depth of said masking layer by said second etch rate to obtain a second time, and adding said first and second times together to obtain said total time.
5 more elements
A method for etching an ultra-shallow channel, comprising the steps of:
- providing a substrate of a first material;
- coating said first material with a photoresist layer;
- defining a pattern in said photoresist layer;
- transferring said pattern into said first material using a dry etching process selective for a material other than said first material until a desired depth of said ultra-shallow channel is achieved in said first material.
1 more element
A method for etching an ultra-shallow channel in a workpiece, comprising the steps of:
- providing a substrate of a first material;
- forming a layer of a second material on at least part of said first material;
- coating said layer with a photoresist;
- defining a pattern in said photoresist;
- and transferring said pattern into said layer using a dry etching process selective for said first material until a desired depth of said ultra-shallow channel is achieved in said second material.
2 more elements
A method according to 28, further comprising the step of passivating all exposed surfaces by thermally growing silicon oxide or depositing a passivating film on all exposed surfaces.
A method for creating a structure that is attached to a substrate only at designated anchor points, thus permitting free movement of said structure except at said anchor points, comprising the steps of:
- providing a workpiece initially consisting of a substrate of a first material;
- forming a layer of a second material on at least part of said first material;
- coating said layer with a photoresist;
- defining a pattern for said anchor points in said photoresist;
- transferring said pattern into said layer using a dry etching process selective for said first material until a depth of said pattern in said second material extends to said substrate;
- depositing said first material in said pattern, thereby filling said pattern;
- smoothing said first material until the exposed side of said first material is coplanar with an exposed side of said second material;
- depositing said first material on said workpiece followed by patterning said first material;
- and etching, using a wet etch, to remove said second material, thereby leaving said patterned first material and said substrate connected only by non-patterned regions of said workpiece.
6 more elements
A method for etching a channel, comprising the steps of:
- providing a substrate of a first material;
- forming a masking layer of a second material on at least part of said first material;
- coating said masking layer with a first photoresist layer;
- defining a first pattern for a first segment of said channel in said first photoresist layer;
- transferring said first pattern into said masking layer using a dry etching process selective for said second material at a first etch rate until said first material is exposed;
- etching, at a second etch rate, said exposed first material using said dry etching process until a desired depth of said first segment of said channel is achieved in said first material;
- removing said first photoresist layer from said masking layer;
- coating said masking layer and said first segment with a second photoresist layer;
- defining a second pattern for a second segment of said channel in said second photoresist layer;
- transferring said second pattern into said masking layer using said dry etching process selective for said second material until said first material is exposed;
- etching said exposed first material using said dry etching process until a desired depth of said second segment of said channel is achieved in said first material, wherein said first and second segments have different depths;
- and removing said second photoresist layer from said masking layer and said first segment.
9 more elements
A method for etching a channel in a workpiece, comprising the steps of:
- providing a substrate of a first material as an initial form of said workpiece;
- forming a masking layer of a second material on at least part of said first material;
- coating said workpiece with a first photoresist layer;
- defining a first pattern for a first segment of said channel in said first photoresist layer;
- transferring said first pattern into said masking layer using a dry etching process selective for said second material until said first material is exposed;
- removing said first photoresist layer from said workpiece;
- coating a second photoresist layer on said workpiece;
- defining a second pattern for a second segment of said channel on said second photoresist layer, wherein said second pattern includes said first pattern as a subset;
- dry etching, after the step of defining said second pattern, said first pattern into said first material for a first period of time;
- transferring said second pattern into said masking layer using dry etching;
- and dry etching simultaneously, using said dry etching process and after the step of transferring said second pattern, said first and second patterns for a second period of time, such that the planar dimensions of said first pattern and said second pattern are reproduced in said substrate.
8 more elements
A method for etching a channel in a workpiece, comprising the steps of:
- providing a substrate of a first material as an initial form of said workpiece;
- forming a masking layer of a second material on said workpiece;
- coating a first photoresist layer on said masking layer;
- defining a first pattern for first and second segments of said channel on said first photoresist layer;
- transferring said first pattern into said masking layer to a depth of an interface between said first material and said second material using dry etching;
- removing said first photoresist layer from said workpiece;
- coating a second photoresist layer on said workpiece;
- defining a second pattern on said workpiece, wherein said second pattern corresponds to said first segment of said channel;
- dry etching, after the step of defining said second pattern, said second pattern into said first material for a first period of time;
- removing said second photoresist layer from said workpiece;
- dry etching simultaneously, using said dry etching process and after the step of dry etching said second pattern, said first and second segments for a second period of time, such that the planar dimensions of said first segment and said second segment are reproduced in said substrate.
8 more elements
A method for making a plurality of posts in an ultra-shallow channel in a workpiece, comprising the steps of:
- providing a substrate of a first material;
- forming a layer of a second material on at least part of said first material;
- coating said layer with a photoresist;
- defining a pattern for said plurality of posts in said photoresist such that said plurality of posts are masked from etching;
- and transferring said pattern into said layer using a dry etching process selective for said first material until a desired depth of said ultra-shallow channel is achieved in said second material.
2 more elements
A method for etching a channel, comprising the steps of:
- providing a substrate of a first material;
- forming a masking layer of a second material on at least part of said first material;
- coating said masking layer with a first photoresist layer;
- defining a first pattern for a first segment and a second segment of said channel in said first photoresist layer;
- transferring said first pattern into said masking layer using a dry etching process selective for said second material at a first etch rate until said first material is exposed;
- etching, at a second etch rate, said exposed first material using said dry etching process until a desired depth of said first and second segments of said channel is achieved in said first material;
- removing said first photoresist layer from said masking layer;
- coating said masking layer and said first and second segments with a second photoresist layer;
- defining a second pattern for a third segment of said channel in said second photoresist layer;
- transferring said second pattern into said masking layer using said dry etching process selective for said second material until said first material is exposed;
- etching said exposed first material using said dry etching process until a desired depth of said third segment of said channel is achieved in said first material, wherein said third segment is a different depth from said desired depth of said first and second segments;
- and removing said second photoresist layer from said masking layer and said first and second segments.
9 more elements
Dependencies are inferred from the claim text.