US2004119067A1PendingUtilityA1

Gallium nitride materials and methods

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Assignee: NITRONEX CORPPriority: Dec 14, 2000Filed: Sep 30, 2003Published: Jun 24, 2004
Est. expiryDec 14, 2020(expired)· nominal 20-yr term from priority
Inventors:T. Warren Weeks, Jr.Edwin L. PinerThomas GehrkeKevin J. Linthicum
H10P 14/3458H10P 14/3416H10P 14/3254H10P 14/3252H10P 14/3216H10P 14/3211H10P 14/2926H10P 14/2925H10P 14/2922H10P 14/2905H10P 14/24C30B 23/02H10D 62/8503H10D 62/852H10D 62/826H10D 62/824H10D 62/405H10D 62/115H10D 62/40H10D 30/4755H10D 30/60H10D 30/015H10H 20/01335H10H 20/825H10H 20/815H10H 20/812H10H 20/811H10H 20/0137H10H 20/0133H10D 30/475H10D 62/8164C30B 25/02C30B 29/406Y10T428/265C30B 25/18Y10T428/26C30B 29/403C30B 29/06Y10T428/24942C30B 29/68C30B 25/183C30B 23/025
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Claims

Abstract

The invention provides semiconductor materials including a gallium nitride material layer formed on a silicon substrate and methods to form the semiconductor materials. The semiconductor materials include a transition layer formed between the silicon substrate and the gallium nitride material layer. The transition layer is compositionally-graded to lower stresses in the gallium nitride material layer which can result from differences in thermal expansion rates between the gallium nitride material and the substrate. The lowering of stresses in the gallium nitride material layer reduces the tendency of cracks to form. Thus, the invention enables the production of semiconductor materials including gallium nitride material layers having few or no cracks. The semiconductor materials may be used in a number of microelectronic and optical applications.

Claims

exact text as granted — not AI-modified
What is claimed is:  
     
         1 . A semiconductor material comprising: 
 a silicon substrate;    a compositionally-graded transition layer formed over the silicon substrate; and    a gallium nitride material layer formed over the transition layer.    
     
     
         2 . The semiconductor material of  claim 1 , wherein the composition of the transition layer is graded continuously across the thickness of the layer.  
     
     
         3 . The semiconductor material of  claim 1 , wherein the composition of the transition layer is graded discontinuously across the thickness of the layer.  
     
     
         4 . The semiconductor material of  claim 1 , wherein the transition layer comprises an alloy of gallium nitride selected from the group consisting of Al x In y Ga (1−x−y) N, In y Ga (1−y) N, and Al x Ga (1−x) N.  
     
     
         5 . The semiconductor material of  claim 4 , wherein the concentration of gallium in the transition layer is graded.  
     
     
         6 . The semiconductor material of  claim 4 , wherein x and/or y is varied from a first value at a back surface of the transition layer to a second value at a front surface of the transition layer, wherein the back surface is closer to the substrate than the front surface.  
     
     
         7 . The semiconductor material of  claim 6 , wherein the sum of the value of x and the value of y at the back surface is greater than 0.4.  
     
     
         8 . The semiconductor material of  claim 6 , wherein the sum of the value of x and the value of y at the back surface is greater than 0.8.  
     
     
         9 . The semiconductor material of  claim 6 , wherein the transition layer comprises Al x In (1−x) N at the back surface of the transition layer in contact with the silicon substrate.  
     
     
         10 . The semiconductor material of  claim 6 , wherein the sum of the value of x and the value of y at the front surface is less than 0.3.  
     
     
         11 . The semiconductor material of  claim 6 , wherein the transition layer comprises GaN at a front surface of the transition layer in contact with the gallium nitride material layer and is free of gallium at a back surface of the transition layer in contact with the substrate.  
     
     
         12 . The semiconductor material of  claim 4 , wherein the transition layer comprises Al x Ga (1−x) N.  
     
     
         13 . The semiconductor material of  claim 4 , wherein the value of x decreases in a direction away from the silicon substrate.  
     
     
         14 . The semiconductor material of  claim 4 , wherein the value of y remains constant across the transition layer.  
     
     
         15 . The semiconductor material of  claim 1 , wherein the transition layer comprises a superlattice.  
     
     
         16 . The semiconductor material of  claim 15 , wherein the superlattice includes a series of alternating Al x In y Ga (1−x−y) N and Al a In b Ga (1−a−b) N layers.  
     
     
         17 . The semiconductor material of  claim 16 , wherein the of value of x, y, a, and b are constant across respective layers and the thickness of the respective layers is varied across the transition layer.  
     
     
         18 . The semiconductor material of  claim 1 , wherein the transition layer has a thickness between about 0.03 micron and about 20 microns.  
     
     
         19 . The semiconductor material of  claim 1 , wherein the gallium nitride material layer comprises GaN.  
     
     
         20 . The semiconductor material of  claim 1 , wherein the gallium nitride material layer comprises Al x In y Ga (1−x−y) N.  
     
     
         21 . The semiconductor material of  claim 1 , wherein the gallium nitride material layer has a thickness of greater than 0.75 micron.  
     
     
         22 . The semiconductor material of  claim 1 , wherein the semiconductor material forms a semiconductor device.  
     
     
         23 . The semiconductor material of  claim 22 , wherein the semiconductor material forms an LED.  
     
     
         24 . The semiconductor material of  claim 22 , wherein the semiconductor material forms a laser diode.  
     
     
         25 . The semiconductor material of  claim 22 , wherein the semiconductor material forms a FET.  
     
     
         26 . The semiconductor material of  claim 1 , wherein the gallium nitride material layer has a crack level of less than 0.005 μm/μm 2 .  
     
     
         27 . The semiconductor material of  claim 1 , wherein the gallium nitride material layer has a crack level of less than 0.001 μm/μm 2    
     
     
         28 . The semiconductor material of  claim 1 , wherein the gallium nitride material layer is substantially free of cracks.  
     
     
         29 . The semiconductor material of  claim 1 , wherein the gallium nitride material layer is monocrystalline.  
     
     
         30 . The semiconductor material of  claim 1 , wherein the silicon substrate has a thickness of greater than 250 micron.  
     
     
         31 . The semiconductor material of  claim 1 , wherein the silicon substrate is textured.  
     
     
         32 . The semiconductor material of  claim 1 , further comprising an intermediate layer formed over the silicon substrate and under the transition layer.  
     
     
         33 . The semiconductor material of  claim 1 , wherein the intermediate layer has a constant composition.  
     
     
         34 . The semiconductor material of  claim 1 , wherein the intermediate layer comprises an alloy of gallium nitride selected from the group consisting of Al x In y Ga (1−x−y) N, In y Ga (1−y) N, and Al x Ga (1−x) N.  
     
     
         35 . The semiconductor material of  claim 1 , wherein the silicon substrate comprises a silicon wafer.  
     
     
         36 . A semiconductor material comprising: 
 a silicon substrate;    a gallium nitride material layer formed over the silicon substrate, the gallium nitride material layer having a crack level of less than 0.005 μm/μm 2 .    
     
     
         37 . The semiconductor material of  claim 36 , wherein the gallium nitride material layer comprises GaN.  
     
     
         38 . The semiconductor material of  claim 36 , wherein the gallium nitride material layer comprises an alloy of gallium nitride selected from the group consisting of Al x In y Ga (1−x−y) N, In y Ga (1−y) N, and Al x Ga (1−x) N.  
     
     
         39 . The semiconductor material of  claim 36 , wherein the gallium nitride material layer has a thickness of greater than 0.5 micron.  
     
     
         40 . The semiconductor material of  claim 36 , wherein the gallium nitride material layer has a thickness of greater than 1.0 micron.  
     
     
         41 . The semiconductor material of  claim 36 , wherein the gallium nitride material layer has a crack level of less than 0.001 μm/μm 2 .  
     
     
         42 . The semiconductor material of  claim 36 , wherein the gallium nitride material layer is substantially free of cracks.  
     
     
         43 . The semiconductor material of  claim 36 , wherein the gallium nitride material layer is monocrystalline.  
     
     
         44 . The semiconductor material of  claim 36 , wherein the silicon substrate comprises a silicon wafer.  
     
     
         45 . A semiconductor structure comprising: 
 a silicon substrate; and    a gallium nitride material layer formed over the silicon substrate and having a thickness of greater than 0.5 micron,    wherein the semiconductor structure forms a semiconductor device.    
     
     
         46 . The semiconductor structure of  claim 45 , wherein the gallium nitride material layer has a thickness of greater than 1.0 micron.  
     
     
         47 . The semiconductor material of  claim 45 , wherein the silicon substrate comprises a silicon wafer.  
     
     
         48 . The semiconductor structure of  claim 45 , wherein the semiconductor structure forms an LED.  
     
     
         49 . The semiconductor structure of  claim 45 , wherein the semiconductor structure forms a laser diode.  
     
     
         50 . The semiconductor structure of  claim 45 , wherein the semiconductor structure forms a FET.  
     
     
         51 . The semiconductor structure of  claim 45 , wherein the gallium nitride material layer has a crack level of less than 0.005 μm/μm 2 .  
     
     
         52 . The semiconductor structure of  claim 45 , wherein the gallium nitride material layer has a crack level of less than 0.001 μm/μm 2 .  
     
     
         53 . The semiconductor structure of  claim 45 , wherein the gallium nitride material layer is substantially free of cracks.  
     
     
         54 . A method of producing a semiconductor material comprising: 
 forming a compositionally-graded transition layer over a silicon substrate; and    forming a gallium nitride material layer over the transition layer.    
     
     
         55 . The method of  claim 54 , wherein the composition of the transition layer is graded continuously across the thickness of the layer.  
     
     
         56 . The method of  claim 54 , wherein the transition layer comprises an alloy of gallium nitride selected from the group consisting of Al x In y Ga (1−x−y) N, In y Ga (1−y) N, and Al x Ga (1−x) N.  
     
     
         57 . The method of  claim 54 , wherein the concentration of gallium in the transition layer is graded.  
     
     
         58 . The method of  claim 56 , wherein the value of x decreases in a direction away from the silicon substrate.  
     
     
         59 . The method of  claim 56 , wherein the transition layer comprises Al x Ga (1−x) N.  
     
     
         60 . The method of  claim 54 , wherein the transition layer comprises a superlattice including a series of alternating Al x In y Ga (1−x−y) N/Al a In b Ga (1−a−b) N layers.  
     
     
         61 . The method of  claim 54 , wherein the gallium nitride material layer comprises GaN.  
     
     
         62 . The method of  claim 54 , wherein the gallium nitride material layer comprises Al x In y Ga (1−x−y) N.  
     
     
         63 . The method of  claim 54 , further comprising processing the semiconductor material to form at least one semiconductor device.  
     
     
         64 . The method of  claim 54 , wherein the gallium nitride material layer has a crack level of less than 0.005 μm/μm 2 .  
     
     
         65 . The method of  claim 54 , wherein the gallium nitride material layer has a crack level of less than 0.001 μm/μm 2 .  
     
     
         66 . The method of  claim 54 , wherein the gallium nitride material layer is substantially free of cracks.  
     
     
         67 . The method of  claim 54 , wherein the gallium nitride material layer is monocrystalline.  
     
     
         68 . The method of  claim 54 , further comprising forming an intermediate layer over the silicon substrate and under the transition layer.  
     
     
         69 . A method of producing a semiconductor material comprising: 
 forming a gallium nitride material layer formed over a silicon substrate, the gallium nitride material layer having a crack level of less than 0.005 μm/μm 2      
     
     
         70 . The method of  claim 69 , wherein the gallium nitride material layer comprises GaN.  
     
     
         71 . The method of  claim 69 , wherein the gallium nitride material layer has a thickness of greater than 1.0 micron.  
     
     
         72 . The method of  claim 69 , wherein the gallium nitride material layer has a crack level of less than 0.001 μm/μm 2 .  
     
     
         73 . The method of  claim 69 , wherein the gallium nitride material layer is substantially free of cracks.  
     
     
         74 . The method of  claim 69 , wherein the gallium nitride material layer is monocrystalline.  
     
     
         75 . A method of forming a semiconductor structure comprising: 
 forming a semiconductor structure comprising a silicon substrate, and a gallium nitride material layer formed over the silicon substrate and having a thickness of greater than 0.5 micron.    
     
     
         76 . The method of  claim 75 , wherein the gallium nitride material layer has a thickness of greater than 1.0 micron.  
     
     
         77 . The method of  claim 75 , wherein the gallium nitride material layer has a thickness of greater than 2.0 microns.  
     
     
         78 . The method of  claim 75 , wherein the semiconductor structure forms an LED.  
     
     
         79 . The method of  claim 75 , wherein the semiconductor structure forms a laser diode.  
     
     
         80 . The method of  claim 75 , wherein the semiconductor structure forms a FET.  
     
     
         81 . The method of  claim 75 , wherein the gallium nitride material layer has a crack level of less than 0.005 μm/μm 2 .  
     
     
         82 . The method of  claim 75 , wherein the gallium nitride material layer has a crack level of less than 0.001 μm/μm 2 .  
     
     
         83 . The method of  claim 75 , wherein the gallium nitride material layer is substantially free of cracks.  
     
     
         84 . A semiconductor material comprising: 
 a silicon (100) substrate; and    a gallium nitride material layer having a Wurtzite structure formed over the silicon substrate.    
     
     
         85 . The semiconductor material of  claim 84 , further comprising a compositionally-graded transition layer formed between the silicon (100) substrate and the gallium nitride material layer.

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