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Trench Refill with Chemical Vapor Deposition Mixed Glasses

IP.com Disclosure Number: IPCOM000051874D
Original Publication Date: 1981-Mar-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 3 page(s) / 37K

Publishing Venue

IBM

Related People

Lever, RF: AUTHOR [+2]

Abstract

Techniques are known for cutting trenches in single crystal silicon and refilling them with dielectrics, primarily SiO(2). Processes for using fritted glasses to fill the trenches are also known. This article proposes using chemical vapor deposition (CVD) for filling the trenches, but including in the reactant gas stream compounds such as GeH(4), GeCl(4) B(2)H(6), BCL(3) so that germanosilicate, borosilicate or other mixed glasses may be deposited. This would be in addition to the usual silicon-containing species, e.g., SiCl(4), SiH(4) and oxidant gasses such as N(2)O, CO(2) O(2), H(2)O, etc., which are at present used to deposit pure SiO(2).

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Trench Refill with Chemical Vapor Deposition Mixed Glasses

Techniques are known for cutting trenches in single crystal silicon and refilling them with dielectrics, primarily SiO(2). Processes for using fritted glasses to fill the trenches are also known. This article proposes using chemical vapor deposition (CVD) for filling the trenches, but including in the reactant gas stream compounds such as GeH(4), GeCl(4) B(2)H(6), BCL(3) so that germanosilicate, borosilicate or other mixed glasses may be deposited. This would be in addition to the usual silicon-containing species, e.g., SiCl(4), SiH(4) and oxidant gasses such as N(2)O, CO(2) O(2), H(2)O, etc., which are at present used to deposit pure SiO(2).

Through control of gases introduced during the deposition, the composition of the glass can be controlled. This provides control of the linear expansion coefficient and viscosity of the deposited glass. The properties of the mixed glass can thereby be adjusted to match the receiving substrate and eliminate stress. In order to prevent intrinsic stress from developing, deposition of the mixed glass would be above the setting or annealing temperature for the mixture. For the case of the GeO(2)-SiO(2) glass system, linear expansion coefficients range from 5 x 10/-7/ to 75 x 10/-7/ with setting temperatures from 1100 degrees C-500 degrees C. This range covers linear coefficient of expansion values of Si as well as many other materials (Ge, GaAs, Al(2)O(3), Si(3)N(4)).

Using CVD-deposited mixed glasses has the following advantages: 1. Convenience and cleanliness associated with CVD systems, which are presently used for depositing pure SiO(2). Very little change in systems would be needed to achieve mixed glasses in place of pure SiO(2) 2. Using mixed glasses enables the expansion coefficient and viscosity, hence, built-in stresses, to be adjusted. For example, in the GeO(2)-SiO(2) system, pure SiO(2) has a linear expansion coefficient of 5x10/-7/ and requires a temperature of 1100 degrees...