Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
245 words
A method of manufacturing an insulated gate field effect transistor, which method comprises providing a conductive gate layer on an insulating layer on one surface of a semiconductor body to form an insulated gate structure having a conductive gate region, introducing impurities into the semiconductor body to form a source region of one conductivity type within a body region of the opposite conductivity type, part of the body region forming a channel area underlying the gate region, growing insulating material on the surface of the semiconductor body to cover the insulated gate structure, and shorting the source region to the body region by opening a contact window in the insulating layer on the one surface so as to expose a surface of the source region, providing a masking region covering the surface of the source region so as to leave an area of the source region exposed, etching away the said exposed area of the source region to expose an underlying area or areas of the body region, removing the masking region and providing metallisation within the contact window to short the exposed area of the body region to the source region, characterised by providing the masking region covering the surface of the source region so that the masking region extends completely across the contact window in one direction so that the exposed area of the source region has a periphery which is defined partly by the contact window and partly by the masking region.
Claim 2
Independent Claim
245 words
A method of manufacturing an insulated gate field effect transistor, which method comprises providing a conductive gate layer on an insulating layer on one surface of a semiconductor body to form an insulated gate structure having a conductive gate region, introducing impurities into the semiconductor body to form a source region of one conductivity type within a body region of the opposite conductivity type, part of the body region forming a channel area underlying the gate region, growing insulating material on the surface of the semiconductor body to cover the insulated gate structure, and shorting the source region to the body region by opening a contact window in the insulating layer on the one surface so as to expose a surface of the source region, providing a masking region covering the surface of the source region so as to leave an area of the source region exposed, etching away the said exposed area of the source region to expose an underlying area or areas of the body region, removing the masking region and providing metallisation within the contact window to short the exposed area of the body region to the source region, characterised by providing the masking region covering the surface of the source region so that the masking region extends completely across the contact window in one direction so that the exposed area of the source region has a periphery which is defined partly by the contact window and partly by the masking region.
Claim 3
Dependent Claim
43 words
A method according to Claim 1, which method comprises opening the contact window by etching the insulating material anisotropically towards the surface of the semiconductor body so that insulating material remains on edges of the insulated gate structure to define the contact window.
Claim 4
Dependent Claim
63 words
A method according to Claim 1 or 2, wherein the step of providing the masking region comprises providing a plurality of masking regions each extending completely across the contact window so as to define a plurality of exposed areas of the source region, each exposed area having a periphery defined partly by the contact window and partly by one or more masking regions.
Claim 5
Independent Claim
55 words
A method according to any preceding claim, wherein the step of opening the contact window comprises opening an elongate contact window and the or each masking region is provided on the insulating layer so as to extend completely across the width of the contact window but only partly across the length of the contact window.
Claim 6
Dependent Claim
74 words
A method according to Claim 3, wherein the step of opening the contact window comprises opening an elongate contact window and the step of providing the masking region comprises providing a plurality of substantially mutually parallel masking regions extending completely across the contact window but spaced-apart in the direction of the length of the contract window so as to define a number of spaced-apart exposed areas of the source region within the contact window.
Claim 7
Dependent Claim
28 words
A method according to Claim 5, wherein the masking regions extending over the contact window are equally spaced-apart in the direction of the length of the contact window.
Claim 8
Dependent Claim
38 words
A method according to Claim 4, 5 or 6, wherein the or each masking region is defined by apertures formed in a masking layer, the width of each aperture being larger than the width of the contact window.
Claim 9
Independent Claim
42 words
A method according to any preceding claim, wherein the masking region(s) is(are) provided so that the or each exposed area of the source region is equal in area to the or each area of the source region covered by the masking region(s).
Claim 10
Independent Claim
58 words
A method according to any preceding claim, further comprising introducing further impurities of the opposite conductivity type through the contact window after etching to expose the underlying area(s) of the body region but before removing the masking region(s) so as to increase the surface doping of the exposed body region(s) prior to providing metallisation in the contact window.
Claim 11
Independent Claim
88 words
A method according to any preceding claim, wherein impurities are introduced into the semiconductor body to provide a respective source region within an associated body region at each of two opposed sides of the gate region so that a part of each body region forms a respective channel area underlying the associated side of the gate region and wherein each source region is shorted to the associated body region as claimed in any one of the preceding claims, a respective contact window being opened over each source region.