Cvd reactor and substrate holder for a cvd reactor

Abstract

The invention relates to a CVD reactor, with a process chamber ( 4 ) which is arranged therein and into which a process gas can be fed by means of a gas inlet member ( 2 ), with a substrate holder ( 3 ) which, on the upper side ( 3 ′) thereof facing the process chamber ( 4 ), has one or more pockets ( 5 ) which are designed in such a manner that one substrate ( 7 ) in each case rests only on selected, raised support regions ( 6 ), and with a heating system ( 9 ) which is arranged below the substrate holder ( 3 ) and is spaced apart from the lower side ( 3 ″) of the substrate holder ( 3 ), wherein the lower side ( 3 ″) of the substrate holder ( 3 ) is configured differently in a central region (b) with respect to the heat transmission from the heating system ( 9 ) to the substrate holder ( 3 ), which central region is located under a central zone of the pocket ( 5 ), than in a surrounding region (a) which surrounds the central region (a) and is located below a zone close to the edge of the pocket ( 5 ). The heating system ( 9 ) is intended to be designed as a substantially planar heat source. A gas flushing device ( 11 ) is provided in order to flush the gap ( 12 ) with flushing gases of different heat conductivity. The gap ( 12 ) has such a gap height (s, t), that, upon a change of a first flushing gas with a first heat conductivity to a second flushing gas with a second heat conductivity, the supply of heat from the heating system ( 9 ) to the substrate holder ( 3 ) changes differently in the circumferential region (a) than in the central region (b).

1 . A CVD reactor having a reactor housing ( 1 ), a process chamber ( 4 ) arranged therein, into which at least one process gas can be fed by means of a gas inlet body ( 2 ), having a substrate holder ( 3 ), which has, on its top side ( 3 ′) facing toward the process chamber ( 4 ), one or more pockets ( 5 ), which are formed so that respectively one substrate ( 7 ) only rests on selected support regions ( 6 ) raised in relation to a base ( 5 ′) of the one or more pockets ( 5 ), having a heater ( 9 ) arranged underneath the substrate holder ( 3 ), which is spaced apart by a gap ( 12 ) from a bottom side ( 3 ″) of the substrate holder ( 3 ), wherein the bottom side ( 3 ″) of the substrate holder ( 3 ) has a depression ( 8 ) in a central region (b) lying under a middle zone of the one or more pockets ( 5 ) or has a different reflectivity than in a surrounding region (a), which surrounds the central region (b) and lies underneath an edge-proximal zone of the one or more pockets ( 5 ), so that heat transfer from a heater ( 9 ) to the substrate holder ( 3 ) is different in the central region (b) than in the surrounding region (a), characterized in that the heater ( 9 ) is implemented as an essentially flat heat source, which extends underneath an entire region of the substrate holder ( 3 ) occupied with the one or more packets ( 5 ), a gas flushing unit ( 11 ) is provided to flush the gap ( 12 ) with flushing gases of various thermal conductivities, and the gap ( 12 ) has a gap height (s, t) such that in the event of a change from a first flushing gas having a first thermal conductivity to a second flushing gas having a second thermal conductivity, the heat supply from the heater ( 9 ) to the substrate holder ( 3 ) changes differently in the surrounding region (a) than in the central region (b). 
     
     
         2 . The CVD reactor according to  claim 1 , characterized in that the gap height (t, t′, t″) of the gap ( 12 ) under the central region (b) is different from the gap height (s) under the surrounding region (a). 
     
     
         3 . (canceled) 
     
     
         4 . The CVD reactor according to  claim 1 , characterized in that a base ( 5 ′,  8 ′) of the one or more pockets ( 5 ) or the recess ( 8 ) curves in a bowl shape. 
     
     
         5 . The CVD reactor according to  claim 4 , characterized in that the curve of the base ( 5 ′,  8 ′) is approximated by a stepped shape. 
     
     
         6 . The CVD reactor according to  claim 1 , characterized in that the bottom side ( 3 ′) of the substrate holder ( 3 ) has a different reflectivity in the central region (b) than in the surrounding region (a). 
     
     
         7 . The CVD reactor according to  claim 1 , characterized in that the central region (b) and/or the surrounding region (a) is coated with a reflective coating. 
     
     
         8 . The CVD reactor according to  claim 1 , characterized in that the heater ( 9 ) is formed by a heating wire ( 10 ) arranged in a spiral. 
     
     
         9 . A method for depositing a plurality of layers arranged one on top of another in respectively one process step on a substrate ( 7 ) in a CVD reactor, having a reactor housing ( 1 ), a process chamber ( 4 ) arranged therein, into which at least one process as can be fed by means of a gas inlet body ( 2 ), having a substrate holder ( 3 ), which has, on its top side ( 3 ′) facing toward the process chamber ( 4 ), one or more pockets ( 5 ), which are formed so that respectively one substrate ( 7 ) only rests on selected support regions ( 6 ) raised in relation to a base ( 5 ′) of the one or more pockets ( 5 ), having a heater ( 9 ) arranged underneath the substrate holder ( 3 ), which is spaced apart by a gap ( 12 ) from a bottom side ( 3 ″) of the substrate holder ( 3 ), wherein the bottom side ( 3 ″) of the substrate holder ( 3 ) has a depression ( 8 ) in a central region (b) lying under a middle zone of the one or more pockets ( 5 ) or has a different reflectivity than in a surrounding region (a), which surrounds the central region (b) and lies underneath an edge-proximal zone of the one or more pockets ( 5 ), so that heat transfer from a heater ( 9 ) to the substrate holder ( 3 ) is different in the central region (b) than in the surrounding region (a), characterized in that the heater ( 9 ) is implemented as an essentially flat heat source, which extends underneath an entire region of the substrate holder ( 3 ) occupied with the one or more pockets ( 5 ), a gas flushing unit ( 11 ) is provided to flush the gap ( 12 ) with flushing gases of various thermal conductivities, and the gap ( 12 ) has a gap height (s, t) such that in the event of a change from a first flushing gas having a first thermal conductivity to a second flushing gas having a second thermal conductivity, the heat supply from the heater ( 9 ) to the substrate holder ( 3 ) changes differently in the surrounding region (a) than in the central region (b), wherein, in at least one first process step, a first layer having a first composition is deposited at a first temperature and, in at least one second process step, a second layer having a second composition is deposited at a second temperature, wherein the two compositions and the two temperatures are different from one another, characterized in that, in the first process step, a first flushing gas or flushing gas mixture is fed into the gap ( 12 ) and, in the second process step, a second flushing gas or flushing gas mixture is fed into the gap, wherein the first flushing gas or flushing gas mixture differs from the second flushing gas or flushing gas mixture at least by way of its thermal conductivity. 
     
     
         10 . The method according to  claim 9 , characterized in that, in the first process step, the heat transport from the heater ( 9 ) to the substrate holder ( 3 ) is heat-radiation-dominated and, in the second step, it is heat-conduction-dominated, at least in one of the two regions (a, b). 
     
     
         11 . The method according to  claim 9 , characterized in that, in the first process step, a mean temperature in a middle zone of the base ( 5 ′) of the one or more pockets ( 5 ) approximately corresponds to a mean temperature of an edge region of the base ( 5 ′) and, in the second process step, these two temperatures are different from one another. 
     
     
         12 . A substrate holder having one or more pockets ( 5 ), which have a support region, formed as a rib ( 6 ) running along their edges ( 5 ″) which support region, is raised in relation to the base ( 5 ′) of the one or more pockets ( 5 ), for substrate ( 7 ), and from the edge ( 5 ″) of which multiple projections ( 17 ) protrude into the one or more pockets ( 5 ), to hold the edge ( 7 ′) of the substrate ( 7 ) spaced apart from the edge ( 5 ″) of the one or more pockets ( 5 ), characterized in that the rib ( 6 ) is interrupted in regions of proximate the projections ( 17 ). 
     
     
         13 . The substrate holder according to  claim 12 , characterized in that a circumferential length of the interruptions ( 16 ) approximately corresponds to a circumferential length of the projections ( 17 ).