US 10,072,351 B2 · Methods and apparati for making thin semi-conductor wafers with locally controlled regions that are relatively thicker than other regions and such wafers

Abstract

Semi-conductor wafers with thin and thicker regions at controlled locations may be for Photovoltaics. The interior may be less than 180 microns or thinner, to 50 microns, with a thicker portion, at 180-250 microns. Thin wafers have higher efficiency. A thicker perimeter provides handling strength. Thicker stripes, landings and islands are for metallization coupling. Wafers may be made directly from a melt upon a template with regions of different heat extraction propensity arranged to correspond to locations of relative thicknesses. Interstitial oxygen is less than 6×1017 atoms/cc, preferably less than 2×1017, total oxygen less than 8.75×1017 atoms/cc, preferably less than 5.25×1017. Thicker regions form adjacent template regions having relatively higher heat extraction propensity; thinner regions adjacent regions with lesser extraction propensity. Thicker template regions have higher extraction propensity. Functional materials upon the template also have differing extraction propensities.

Claims21

Dependent claims

A semi-conductor wafer comprising:

a. a first surface;
and
b. a second surface;
c. a first region with a first average thickness in a direction orthogonal to the first surface;
d. a second region with a second average thickness that is thicker than the first average thickness and that is in a selectable location;
and
e. a third region with a third average thickness that is thicker than the first average thickness and that is thinner than the second average thickness.

4 more elements

A method for fabricating a semi-conductor wafer, the method comprising the steps of:

a. providing a molten semi-conductor material, having a surface;
b. providing a template, comprising a porous body comprising:
i. a melt-ward surface;
ii. a back surface;
iii. a first template region having a first heat extraction propensity;
iv. a second template region having a second heat extraction propensity, which is greater than the first heat extraction propensity;
c. providing a differential pressure regime such that pressure at at least a portion of the melt-ward surface is less than pressure at the molten semi-conductor material surface;
and
d. contacting the template melt-ward surface to the surface of the molten semi-conductor material for at least a portion of a contact duration, during which the melt-ward surface and the molten semi-conductor material are in contact with each other, and the differential pressure regime is provided, such that a body of semi-conductor material, solidifies upon the melt-ward surface, which formed body comprises:
i. a first, thinner body region, which has a first thinner body average thickness, the first thinner body region having formed adjacent the first template region;
and
ii. a second, thicker body region, which has a second thicker body average thickness, the second body region having formed adjacent the second template region, the second body average thickness being greater than the first body thickness.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application

15/306,787Filed 17 Apr 2015 · us provisional application

Priority

30 Apr 2014

Published

US 2017/0051429 A123 Feb 2017

Granted

11 Sep 2018

Term ends

Not estimatedThe source records don’t support an estimate.

Classification15 codes

C30B 11/02
Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method: without using solvents
C30B 29/06
Elements: silicon
H10D 62/117
Shapes, relative sizes or dispositions of the regions of the semiconductor bodies; Shapes of the semiconductor bodies: shapes of semiconductor bodies
H10F 10/146
Photovoltaic cells having only PN homojunction potential barriers: back-junction photovoltaic cells, e.g. having interdigitated base-emitter…

Methods and apparati for making thin semi-conductor wafers with locally controlled regions that are relatively thicker than other regions and such wafers

Life of this patent

Methods and apparati for making thin semi-conductor wafers with locally controlled regions that are relatively thicker than other regions and such wafers

Life of this patent

Abstract

Claims21