EP0047140A2
Expired / Lapsed
EP
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Method of converting areas of semiconductor material into single crystal areas
Assignee: Xerox Corp
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Filing: 1981-08-27
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Granted: —
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Expires: 2001-08-27
Abstract
Abstract A method for laser induced conversion of large predefined areas (10) of amorphous or polycrystalline semiconductor material, disposed non-epitaxially upon a substrate (24), into large single crystal areas, by controlling the lateral heat flow out of the melted regions (19) of the areas for causing their recrystallization from a single nucleation site (34) and for suppressing the formation of competitive nucleation sites at their edges.
Inventors
- 👤 David K. Biegelsen
- 👤 Dirk J. Bartelink
- 👤 Noble M. Johnson
- 👤 Marvin D. Moyer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 13:34
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/20; H10P14/38; H10P14/3802; H10P14/3808; H10F; H10F71/00; H10F71/131; H10P14/29; H10P14/2901; H10P14/2922; H10P14/32; H10P14/3202; H10P14/3238; H10P14/3242; H10P14/3244; H10P14/3251; H10P14/34; H10P14/3402; H10P14/3404; H10P14/3411; H10P14/3451; H10P14/381; H10P14/382; H10P34/00; H10P34/40; H10P34/42; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y02P; Y02P70/00; Y02P70/50; Y10; Y10S; Y10S117/00; Y10S117/903; Y10S117/904
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
189 words
A method of converting predefined areas of semiconductor material on a support means into single crystal areas comprising the steps of heating each area with an optical energy source so as to melt the semiconductor material, and allowing the molten semiconductor material to cool and crystallise, the method being characterised by providing optical energy absorbing means in or on said support means adjacent4to and around each of said areas, and providing thermal control means, associated with said optical energy absorbing means, in the region adjacent to and around each area, for affecting the amount of thermal energy absorbed in the region immediately adjacent to and around each area to compensate for preferential heat loss at the edges of each area, said thermal control means establishing a thermal gradient between the central portion of each area and the edges of each area for slowing the rate of cooling at said edges such that as said melted areas cool, each will crystallize from a single nucleation location and competitive nucleation locations at said edges will be suppressed, whereby each of said -areas will be converted to a single crystal when cooled.
Claim 2
Independent Claim
189 words
A method of converting predefined areas of semiconductor material on a support means into single crystal areas comprising the steps of heating each area with an optical energy source so as to melt the semiconductor material, and allowing the molten semiconductor material to cool and crystallise, the method being characterised by providing optical energy absorbing means in or on said support means adjacent4to and around each of said areas, and providing thermal control means, associated with said optical energy absorbing means, in the region adjacent to and around each area, for affecting the amount of thermal energy absorbed in the region immediately adjacent to and around each area to compensate for preferential heat loss at the edges of each area, said thermal control means establishing a thermal gradient between the central portion of each area and the edges of each area for slowing the rate of cooling at said edges such that as said melted areas cool, each will crystallize from a single nucleation location and competitive nucleation locations at said edges will be suppressed, whereby each of said -areas will be converted to a single crystal when cooled.
Claim 3
Dependent Claim
66 words
The method of claim 1 wherein the heating step includes projecting a laser spot and imparting relative motion between said spot and said areas, said spot being elongated such that its short dimension is less than the dimension of each area in the direction of relative movement and its long dimension is greater than the dimension of each area transversely of the direction of relative movement.
Claim 4
Dependent Claim
45 words
The method of claim 1 or claim 2 wherein said step of providing thermal control means comprises depositing one or more dielectric layers upon said optical energy absorbing layer which affect the amount of absorbed optical energy by selective reflection or transmission of said energy.
Claim 5
Dependent Claim
28 words
The method of claim 2 including providing an array of chevron shaped islands having tapered leading edges whose apexes are first crossed by said scanning elongated laser spot.
Claim 6
Dependent Claim
95 words
The method of claim 2 including providing as said support means an amorphous substrate which does not absorb optical energy, providing said optical energy absorbing means by depositing an amorphous or polycrystalline silicon optical energy absorbing layer on said substrate, providing said thermal control means by depositing a first dielectric layer of silicon dioxide on said optical energy absorbing layer and depositing a second dielectric layer of silicon nitride on said oxide layer, and providing said areas of semiconductor material by depositing an array of amorphous or polycrystalline silicon islands on said silicon nitride layer.
Claim 7
Independent Claim
29 words
The method of any one of claims 1 to 5 wherein said step of providing thermal control means comprises forming a moat immediately adjacent to and around each area.
Claim 8
Dependent Claim
30 words
The method of claim 6 including removing a tapering region of material in advance of that edge of each area which is first crossed by said scanning elongated laser spot.
Claim 9
Independent Claim
42 words
The method of any one of claims 1 to 4 including the step of encapsulating each of said areas by depositing over it a dielectric layer for maintaining the upper surface of each area smooth after it has recrystallized from the melt.
Claim 10
Dependent Claim
120 words
The method of claim 2 including providing as said support means an amorphous substrate which does not absorb optical energy, providing said optical energy absorbing means by depositing an amorphous or polycrystalline silicon optical energy absorbing layer on said substrate, providing said thermal control means by first depositing a first dielectric layer of silicon dioxide on said optical energy absorbing layer, providing said areas of semiconductor material by depositing a pattern of amorphous or polycrystalline silicon islands on said first dielectric layer, and depositing a second dielectric layer of silicon nitride over said islands and over said first dielectric layer, the portion of said second dielectric layer overlying said first dielectric layer forming a portion of said thermal control means.
Claim 11
Dependent Claim
88 words
The method of claim 2 including providing as said support means an amorphous substrate which does not absorb optical energy, providing said optical energy absorbing means by depositing an amorphous or polycrystalline silicon optical energy absorbing layer on said substrate, providing said thermal control means by first removing portions of said layer in a pattern so as to define islands with moats therearound in a sea of optical energy absorbing material, and then depositing a dielectric overlayer of silicon nitride on said sea, said moat and said islands.
References Cited (Backward Citations)
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