Method for manufacturing a microfluidic device

Patent metadata

Field	Value
Publication number	US-12595168-B2
Application number	US-202218045287-A
Country	US
Kind code	B2
Filing date	Oct 10, 2022
Priority date	Oct 26, 2021
Publication date	Apr 7, 2026
Grant date	Apr 7, 2026

Abstract

An intermediate structure for a microfluidic device and a method for manufacturing a microfluidic device are provided. The method includes: a) providing a first substrate having a first layer thereon, and a second layer on the first layer; b) forming a first nanopore in the second layer, in such a way that a part of the first layer coincides with a bottom of the first nanopore; c) exposing said part of the first layer to a liquid etchant, thereby forming a cavity under the first nanopore, the cavity having a larger width than a width of the bottom of the first nanopore; d) filling the first nanopore and the cavity with a filling material, thereby forming a first plug; e) forming a bottom fluidic access for the nanopore by removing part of the first substrate and part of the first layer so as to expose the plug; and f) removing the plug, thereby fluidly connecting the bottom fluidic access to the nanopore.

First claim

The invention claimed is:

1 . A method for manufacturing a microfluidic device, the method comprising:
a) providing a first substrate having a first layer thereon, and a second layer on the first layer, wherein the second layer has a bottom surface in contact with a top surface of the first layer, and a top surface facing away from the first layer; b) forming a first nanopore in the second layer in such a way that a part of the first layer coincides with a bottom of the first nanopore, wherein forming the first nanopore comprises a dry etching step; c) exposing said part of the first layer to a liquid etchant, thereby forming a cavity under the first nanopore, the cavity having a larger width (W) than a width (w 1 ) of the bottom of the first nanopore after step c and before step d; d) filling the first nanopore and the entire cavity with a solid filling material, thereby forming a first plug; e) forming a bottom fluidic access for the first nanopore by removing a part of the first substrate and the part of the first layer so as to expose the first plug, and forming a top fluidic access for the first nanopore by providing a third layer over the second layer and the first plug if such a third layer is not already present, and removing part of the third layer so as to expose the first plug; and f) removing the first plug, thereby fluidly connecting the bottom fluidic access to the first nanopore.

2 . The method according to claim 1 , wherein the width (w 1 ′) of the first nanopore after step f is within 1 nm of the width (w 1 ) of the first nanopore between step c and step d, when measured in the plane of the bottom surface of the second layer.

3 . The method according to claim 1 , wherein the first plug comprises amorphous silicon.

4 . The method according to claim 1 , wherein the first nanopore has a width (w 0 ) after step b and before step c ranging from 3 to 50 nm, ranging from 5 to 45 nm, or ranging from 8 to 30 nm, when measured in a plane of the bottom surface of the second layer.

5 . The method according to claim 1 , wherein the first nanopore has a length through the second layer after step b and before step c ranging from 400 nm to 2 μm.

6 . The method according to claim 1 , wherein step b comprises a step b 1 of dry etching a precursor nanopore in the second layer, the precursor nanopore having a width (w 0 ), followed by a step b 2 between step b 1 and step c of narrowing the width (w 0 ) of the precursor nanopore by oxidizing inner walls of the precursor nanopore.

7 . The method according to claim 6 , wherein the width (w 0 ) of the first nanopore before step b 2 ranges from 100 to 300 nm, and wherein a width (w 0 ′) of the first nanopore after step b 2 and before step c ranges from 8 to 30 nm.

8 . The method according to claim 1 , further comprising a step d′ between step d and step e of:
i) covering the first plug with an oxide layer;
ii) planarizing the oxide layer;
iii) bonding a second substrate on the planarized oxide layer, the second substrate comprising a semiconductor layer;
iv) dry etching a second nanopore, aligned with the first nanopore, in the second substrate and the oxide layer, until a part of the first plug coincides with a bottom of the second nanopore, the second nanopore having a width (w 2 ) measured in the plane of the top surface of the semiconductor layer, ranging from 5 to 15 times the width (w 1 ′) of the first nanopore after step f;
v) filling the second nanopore with a solid filling material, thereby forming a second plug;
vi) doping the semiconductor layer on opposite sides of the second nanopore, thereby forming a source region and a drain region;
vii) activating the source region and the drain region by annealing; and
viii) forming metal contacts to the source region and at the drain region.

9 . The method according to claim 8 , further comprising a step of removing the second plug, thereby fluidly connecting the top fluidic access to the second nanopore.

10 . The method according to claim 1 , further comprising a step of removing the second plug, thereby fluidly connecting the top fluidic access to the second nanopore.

11 . The method according to claim 1 , wherein forming the top fluidic access for the first nanopore is performed before forming the bottom fluidic access for the first nanopore.

12 . The method according to claim 1 , wherein step c is performed until a part of the bottom surface of the second layer, around a periphery of the bottom of the first nanopore, is exposed to the liquid etchant.

Assignees

• Imec Vzw

Inventors

• Severi Simone
• Du Bois Bert
• Ray Chaudhuri Ashesh

Classifications

• B81C2201/0133

  Wet etching · CPC title

• B81C1/00087

  Holes · CPC title

• B81B2201/06

  Bio-MEMS · CPC title

• B81B1/004

  Through-holes, i.e. extending from one face to the other face of the wafer · CPC title

• B01L3/502761

  specially adapted for handling suspended solids or molecules independently from the bulk fluid flow, e.g. for trapping or sorting beads or physically stretching molecules · CPC title