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Oxide precipitates in annealed nitrogen-doped 300 mm CZ-SI
Materials Science in Semiconductor Processing 5 (2003) 391–396
Oxide precipitates in annealed nitrogen-doped 300 mm CZ-SI V.D. Akhmetova,b,*, H. Richtera,b, O. Lysytskiyc, R. Wahlichd, T. Muller . d a IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany IHP/BTU Joint Lab, Universitatsplatz 3-4, 03044 Cottbus, Germany . c BTU, Universitatsplatz 3-4, 03044 Cottbus, Germany . d Wacker Siltronic AG, P.O. Box 1140, 84479 Burghausen, Germany
b
Abstract The lateral distribution of oxide precipitates as well as the denuded zone were investigated in a set of 300 mm CZ silicon wafers containing different amounts of nitrogen. Two light scattering methods, infrared light scattering tomography (IR-LST) as well as scanning infrared microscopy (SIRM) were used to characterize the precipitation density and the spatial distribution. The obtained results show that under certain heat treatments a high density of oxide precipitates, more than 1 109 cm 3, can be achieved in the depth of 300 mm wafers. With increasing nitrogen content the radial distribution of precipitates becomes more uniform. A 10–60 mm wide precipitation-free denuded zone was observed. A comparison between IR-LST and SIRM results was performed indicating the dominance of relatively small precipitates. r 2003 Elsevier Science Ltd. All rights reserved. Keywords: 300 mm Silicon; Nitrogen doping; Precipitates; Intrinsic gettering
1. Introduction The application of intrinsic gettering (IG) in the case of 300 mm CZ silicon makes it necessary to find a reliable way for the creation of a large density of oxide precipitates in the depth of the wafer as well as a defectfree denuded zone under the planar surface of the wafer. The direct transfer of the IG technology which was developed for wafers with relatively smaller diameters seems to be problematic. This is due to the tendency towards a decrease of the rate of the oxide precipitation processes with increasing crystal diameter above 200 mm. Changes in either the oxygen content or in the defect can be the cause of relatively slow decay of supersaturated solid solution of oxide in silicon. These circumstances stimulate the search of new and more reliable ways for carrying out a successful process of precipitation of oxygen in silicon. *Corresponding author. IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany. E-mail address: [email protected] (V.D. Akhmetov).
One of such possible ways is based on doping the silicon with nitrogen (N) during the crystal growth [1]. It was found that a relatively small amount of N, in the order of 1014 cm 3 enhances the precipitation of oxygen [2]. The enhanced precipitation of oxygen is interpreted in terms of changes in the ensemble of point defects caused by N. The exact mechanism of impact of N on the precipitation of oxygen is still under study. The results of recent investigations indicate the effective interaction of N with vacancies (V) and intrinsic interstitial atoms as well as the formation of complexes with oxygen [3]. First principle calculations for N point defects in silicon verify that the V2N2 complex is a stable nucleus for oxide precipitation. This complex is formed during crystal growth by reaction of VN2 with V or during heat treatment by a reaction between N2 and V2, [4]. Most of the published results concerning the influence of N on oxide precipitation are obtained on CZ silicon wafers with diameter not greater than 200 mm. Because the conditions of the growth of the 300 mm silicon crystals differ from those at smaller crystal diameters, the initial state of N as well as the set and spatial
1369-8001/03/$ - see front matter r 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S1369-8001(02)00136-1
392
V.D. Akhmetov et al. / Materials Science in Semiconductor Processing 5 (2003) 391–396
distribution of as-grown defects can be different. This can affect oxide precipitation. Moreover, most of the results were obtained from discrete samples of wafers and do not show the whole spatial picture of both, formation of the precipitates as well as the quality of the denuded zone. Recent results of SIRM measurements in some places of a 300 mm wafer show the influence of the nitrogen content on the denuded zone [5]. Therefore, further investigations are needed in order to understand the effectiveness of N doping for successful IG application for the 300 mm materials. The aim of this work was to study systematically the effect of N doping on oxide precipitation in 300 mm silicon, namely the distribution of the precipitates across the wafer as well as denuded zone behavior over all wafers.
2. Experimental Two groups of 300 mm double side polished CZ silicon (1 0 0) wafers were studied. Test wafers were made from three types of specially pulled rods with following material parameters: (a) N undoped (UN), with N content lower than 3 1013 cm 3, (b) low N doped (LN), with the concentration of N in the range from 3 1013 to 3 1014 cm 3 and (c) high N doped (HN) that contained N in concentration of 3 1014– 3 1015 cm 3. The first group consisted of thermally untreated UN and HN wafers. The second group contained UN, LN and HN wafers subjected to annealing 12001C, 2 h in Ar. This annealing served as an activation treatment for the creation of an intrinsic getter and the formation of a COP-free (crystal originated particle) and precipitation-free zone. Oxygen content was in the range of 5–6 1017 cm 3 (FT-IR, New ASTM).
IR-LST:
3. Results and discussion A comparison between IR-LST and SIRM results of measurements is plotted in Fig. 3. A relatively small constant, 4.36 106 cm 3 has been added to both IRLST and SIRM data in order to show on a logarithmic scale all experimental BMD data points (including
SIRM: Microscope
Microscope Polished cleaved surface of wafer
Laser beam 1064 nm
Wafers from both groups were examined by two methods based on light scattering, IR-LST and SIRM. Fig. 1 shows the principal optical schemes of IR-LST and SIRM which were used. In both cases the pump laser beam was directed perpendicular to the planar surface of the wafer. In the IR-LST method the scattered light was collected from directions that were oriented approximately perpendicular to the laser beam. The beam has a wavelength 1064 nm, which allows one to make measurements on arbitrary depth of the wafer due to relatively small absorption. However, this configuration needs the cross sectioned surface. Therefore, this method can be regarded as destructive. In the SIRM method scattered light is detected in the back scattering geometry which allows one to perform nondestructive measurements. The maximal depth of measurement was approx. 120 mm due to the use of a more absorbing probe beam with a wavelength of 980 nm. For preparing the wafers for an IR-LST measurement an abrasive treatment of cleaved wafers has been applied. Fig. 2 illustrates the main steps of this preparation. The stripes of silicon obtained by cleavage of several 300 mm wafers are collected in a bloc and glued one to another. These blocs itself are then glued to supporting blocs (e.g. glass) by means of epoxy glue. This ensemble was afterwards ground, polished and again disconnected by annealing. The obtained stripes were cleaned carefully and individually if needed.
Planar Si surface
Planar Si surface
Laser beam 980 nm
Fig. 1. Principal operating schemes of IR-LST and SIRM to detect oxide precipitates.
V.D. Akhmetov et al. / Materials Science in Semiconductor Processing 5 (2003) 391–396
393
Fig. 2. Group preparation of 300 mm wafers for IR-LST measurements.
10
1010
Light Scattering Defect Density+4.3.106 (cm-3)
SIRM density + 4.3.106 (cm-3)
10
5 points 9
10
X=Y
8
10
Linear fit: Y
X
0.6
109
108
10
1 2 3
7
4 5 6
7
10
106 0
20
40
60
80
100
120
140
160
Distance from the Wafer Edge (mm) 6
10
Fig. 3. Correlation between IR-LST and SIRM measurements.
Fig. 4. Radial distribution of defects in 300 mm silicon wafers. Solid symbols and curves: IR-LST measurements, open symbols and dashed curves: SIRM measurements. 1, 4, 6— HN wafers, 12001C, 2 h; 2, 5—LN wafers, 12001C, 2 h; 3—UN wafers, not annealed.
points with zero density). This constant corresponds to a single precipitate over the entire field of view for the SIRM technique (for IR-LST the field of view is almost the same) and can be regarded as the detection limit. Data were taken from selected points of the set of wafers. From Fig. 3 one can see that the results obtained from SIRM are systematically less than the values obtained from IR-LST when the density of precipitates, determined by IR-LST, exceeds 108 cm 3. We assume that this difference is caused by a relatively low sensitivity of SIRM in the case of small size precipitates. So we have used IR-LST as the main
method in order to receive a more complete picture of precipitation. The distribution of precipitates along wafers containing various levels of N doping is presented in Fig. 4. SIRM data were collected from a depth of 60–120 mm, whereas IR-LST data were obtained from the depth of 300–600 mm. Solid symbols and solid lines correspond to IR-LST, open symbols and dashed lines correspond to SIRM. It can be seen that for the annealed HN material a nearly uniform radial distribution of precipitates is formed. The absolute value of concentration of precipitates exceeds 109 cm 3 for almost all radial
6
10
7
10
8
10
9
10
10
10
IR - LST density + 4.3.106 (cm-3)
V.D. Akhmetov et al. / Materials Science in Semiconductor Processing 5 (2003) 391–396
394
positions. This high density of precipitates allows one to expect a good quality of the intrinsic gettering capability. If the LN material is used a high density of
70
Denuded Zone (µm)
60
50
40
30
20
10 0
20
40
60
80
100
120
140
Distance from Wafer Edge (mm)
Fig. 5. Radial distribution of denuded zone in nitrogen-doped annealed wafers. Upper curve—LN wafer, 12001C, 2 h; lower curve—HN wafer, 12001C, 2 h.
precipitates was reliably formed only in the inner part of the wafer, between center and approximately middle of the radius. Large non-uniformities in the density of precipitates were observed in the outer part of the LN wafers. The detected BMD density varies from 5 106 to 6 108 atoms/cm3. The observed fluctuating behavior of precipitates by changing the N content can be explained in the following manner: for oxygen concentrations of 5– 6.3 1017 atoms/cm3—as present for LN and HN wafers—the precipitation of oxygen proceeds slowly. Adding of N on the LN level enhances the precipitation, but the effect of N is more pronounced in the central part of the wafer where vacancy-type defects dominate. This is expected because both factors, V and N, stimulate oxide precipitation [2,6]. By choosing an appropriate level of N doping (=HN material) it is possible to enhance drastically the oxide precipitation in all wafer parts. The radial distribution of the denuded zone in LN and HN annealed wafers is depicted in Fig. 5. It can be seen that the width of DZ decreases from 50–70 to 15–40 mm with increasing N content. There is a tendency of
Fig. 6. IR-LST cross section of low nitrogen-doped silicon wafer after 12001C, 2 h.
V.D. Akhmetov et al. / Materials Science in Semiconductor Processing 5 (2003) 391–396
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Fig. 7. IR-LST cross section of high nitrogen-doped silicon wafer after 12001C, 2 h.
narrowing of the denuded zone in the outer part of wafer. But in all cases the width of the denuded zone exceeds 12 mm. That seems to be enough for the formation of active layers for most integrated circuits. Typical IR-LST images from cross sectioned wafers including the denuded zone region are presented in Figs. 6 and 7 (LN and HN material, respectively). These images demonstrate the existence of the defect-free denuded zone in both types of materials. Light points correspond to oxide precipitates. The warped line of the silicon–air interface instead of a straight one as well as some large elongated light areas are caused by parasitic scattering from a not ideal angle between planar and cross sectioned surfaces. 4. Conclusion The radial distribution of oxide precipitates as well as the properties of the denuded zone formed in annealed (12001C) 300 mm nitrogen-doped CZ-Si wafers were investigated by means of light scattering methods. Two main results were obtained: 1. The addition of N enhances the density of oxide precipitates and improves the homogeneity of its
distribution especially in the peripheral part of the silicon wafer. Nearly uniform radial profiles of oxide precipitates can be achieved with a range of precipitation density: 1–3 109 cm 3. 2. The width of the denuded zone tends to narrow with increase N doping but remains more than 12 mm across the entire wafer. The obtained results show that annealing of high nitrogen-doped silicon wafers yield a high density of relatively uniform distributed oxide precipitates in the depth over the entire wafer. It leads to the formation of a denuded zone which is sufficiently wide for device applications. Therefore, these results describe a suitable way to achieve an activated intrinsic getter for argon annealed 300 mm silicon wafers.
Acknowledgements This work was supported by the Federal Department of Education and Research of the FRG under contract number 01 M 2973A. The authors alone are responsible for the content.
396
V.D. Akhmetov et al. / Materials Science in Semiconductor Processing 5 (2003) 391–396
References [1] Goto H, Tanaka M, Pan L-S, Kashima K. Jpn J Appl Phys Part 1 2001;40:3944. [2] Sueoka K, Akatsuka M, Yonemura M, Ono T, Eiichi Asayama, Koike Y, Sadamitsu S, GADEST 2001 on Solid State Phenomena, vol. 82–84, 2002. p. 49. . R, Virbulis J, Dornberger E, Schmolke [3] Ammon Wv, Holzl R, Gr.af D. J Cryst Growth 2002;226:19.
[4] Karoui A, Karouri FS, Rozgonyi GA, Hourai M, Sueoka K. Semiconductor Silicon 2002, ECS Proceedings, vol. 2002-2, 2002. p. 670. [5] Muller . T, Siebert W, Messmann K, Walich R, Krottentha. R, Ikari A, Ammon Wv, Semiconductor Silicon ler P, Holz 2002, ECS Proceedings, vol. 2002-2, 2002. p. 194. [6] Voronkov VV, Falster R. J Appl Phys 2002;91:5802.
Oxide precipitates in annealed nitrogen-doped 300 mm CZ-SI V.D. Akhmetova,b,*, H. Richtera,b, O. Lysytskiyc, R. Wahlichd, T. Muller . d a IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany IHP/BTU Joint Lab, Universitatsplatz 3-4, 03044 Cottbus, Germany . c BTU, Universitatsplatz 3-4, 03044 Cottbus, Germany . d Wacker Siltronic AG, P.O. Box 1140, 84479 Burghausen, Germany
b
Abstract The lateral distribution of oxide precipitates as well as the denuded zone were investigated in a set of 300 mm CZ silicon wafers containing different amounts of nitrogen. Two light scattering methods, infrared light scattering tomography (IR-LST) as well as scanning infrared microscopy (SIRM) were used to characterize the precipitation density and the spatial distribution. The obtained results show that under certain heat treatments a high density of oxide precipitates, more than 1 109 cm 3, can be achieved in the depth of 300 mm wafers. With increasing nitrogen content the radial distribution of precipitates becomes more uniform. A 10–60 mm wide precipitation-free denuded zone was observed. A comparison between IR-LST and SIRM results was performed indicating the dominance of relatively small precipitates. r 2003 Elsevier Science Ltd. All rights reserved. Keywords: 300 mm Silicon; Nitrogen doping; Precipitates; Intrinsic gettering
1. Introduction The application of intrinsic gettering (IG) in the case of 300 mm CZ silicon makes it necessary to find a reliable way for the creation of a large density of oxide precipitates in the depth of the wafer as well as a defectfree denuded zone under the planar surface of the wafer. The direct transfer of the IG technology which was developed for wafers with relatively smaller diameters seems to be problematic. This is due to the tendency towards a decrease of the rate of the oxide precipitation processes with increasing crystal diameter above 200 mm. Changes in either the oxygen content or in the defect can be the cause of relatively slow decay of supersaturated solid solution of oxide in silicon. These circumstances stimulate the search of new and more reliable ways for carrying out a successful process of precipitation of oxygen in silicon. *Corresponding author. IHP, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany. E-mail address: [email protected] (V.D. Akhmetov).
One of such possible ways is based on doping the silicon with nitrogen (N) during the crystal growth [1]. It was found that a relatively small amount of N, in the order of 1014 cm 3 enhances the precipitation of oxygen [2]. The enhanced precipitation of oxygen is interpreted in terms of changes in the ensemble of point defects caused by N. The exact mechanism of impact of N on the precipitation of oxygen is still under study. The results of recent investigations indicate the effective interaction of N with vacancies (V) and intrinsic interstitial atoms as well as the formation of complexes with oxygen [3]. First principle calculations for N point defects in silicon verify that the V2N2 complex is a stable nucleus for oxide precipitation. This complex is formed during crystal growth by reaction of VN2 with V or during heat treatment by a reaction between N2 and V2, [4]. Most of the published results concerning the influence of N on oxide precipitation are obtained on CZ silicon wafers with diameter not greater than 200 mm. Because the conditions of the growth of the 300 mm silicon crystals differ from those at smaller crystal diameters, the initial state of N as well as the set and spatial
1369-8001/03/$ - see front matter r 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S1369-8001(02)00136-1
392
V.D. Akhmetov et al. / Materials Science in Semiconductor Processing 5 (2003) 391–396
distribution of as-grown defects can be different. This can affect oxide precipitation. Moreover, most of the results were obtained from discrete samples of wafers and do not show the whole spatial picture of both, formation of the precipitates as well as the quality of the denuded zone. Recent results of SIRM measurements in some places of a 300 mm wafer show the influence of the nitrogen content on the denuded zone [5]. Therefore, further investigations are needed in order to understand the effectiveness of N doping for successful IG application for the 300 mm materials. The aim of this work was to study systematically the effect of N doping on oxide precipitation in 300 mm silicon, namely the distribution of the precipitates across the wafer as well as denuded zone behavior over all wafers.
2. Experimental Two groups of 300 mm double side polished CZ silicon (1 0 0) wafers were studied. Test wafers were made from three types of specially pulled rods with following material parameters: (a) N undoped (UN), with N content lower than 3 1013 cm 3, (b) low N doped (LN), with the concentration of N in the range from 3 1013 to 3 1014 cm 3 and (c) high N doped (HN) that contained N in concentration of 3 1014– 3 1015 cm 3. The first group consisted of thermally untreated UN and HN wafers. The second group contained UN, LN and HN wafers subjected to annealing 12001C, 2 h in Ar. This annealing served as an activation treatment for the creation of an intrinsic getter and the formation of a COP-free (crystal originated particle) and precipitation-free zone. Oxygen content was in the range of 5–6 1017 cm 3 (FT-IR, New ASTM).
IR-LST:
3. Results and discussion A comparison between IR-LST and SIRM results of measurements is plotted in Fig. 3. A relatively small constant, 4.36 106 cm 3 has been added to both IRLST and SIRM data in order to show on a logarithmic scale all experimental BMD data points (including
SIRM: Microscope
Microscope Polished cleaved surface of wafer
Laser beam 1064 nm
Wafers from both groups were examined by two methods based on light scattering, IR-LST and SIRM. Fig. 1 shows the principal optical schemes of IR-LST and SIRM which were used. In both cases the pump laser beam was directed perpendicular to the planar surface of the wafer. In the IR-LST method the scattered light was collected from directions that were oriented approximately perpendicular to the laser beam. The beam has a wavelength 1064 nm, which allows one to make measurements on arbitrary depth of the wafer due to relatively small absorption. However, this configuration needs the cross sectioned surface. Therefore, this method can be regarded as destructive. In the SIRM method scattered light is detected in the back scattering geometry which allows one to perform nondestructive measurements. The maximal depth of measurement was approx. 120 mm due to the use of a more absorbing probe beam with a wavelength of 980 nm. For preparing the wafers for an IR-LST measurement an abrasive treatment of cleaved wafers has been applied. Fig. 2 illustrates the main steps of this preparation. The stripes of silicon obtained by cleavage of several 300 mm wafers are collected in a bloc and glued one to another. These blocs itself are then glued to supporting blocs (e.g. glass) by means of epoxy glue. This ensemble was afterwards ground, polished and again disconnected by annealing. The obtained stripes were cleaned carefully and individually if needed.
Planar Si surface
Planar Si surface
Laser beam 980 nm
Fig. 1. Principal operating schemes of IR-LST and SIRM to detect oxide precipitates.
V.D. Akhmetov et al. / Materials Science in Semiconductor Processing 5 (2003) 391–396
393
Fig. 2. Group preparation of 300 mm wafers for IR-LST measurements.
10
1010
Light Scattering Defect Density+4.3.106 (cm-3)
SIRM density + 4.3.106 (cm-3)
10
5 points 9
10
X=Y
8
10
Linear fit: Y
X
0.6
109
108
10
1 2 3
7
4 5 6
7
10
106 0
20
40
60
80
100
120
140
160
Distance from the Wafer Edge (mm) 6
10
Fig. 3. Correlation between IR-LST and SIRM measurements.
Fig. 4. Radial distribution of defects in 300 mm silicon wafers. Solid symbols and curves: IR-LST measurements, open symbols and dashed curves: SIRM measurements. 1, 4, 6— HN wafers, 12001C, 2 h; 2, 5—LN wafers, 12001C, 2 h; 3—UN wafers, not annealed.
points with zero density). This constant corresponds to a single precipitate over the entire field of view for the SIRM technique (for IR-LST the field of view is almost the same) and can be regarded as the detection limit. Data were taken from selected points of the set of wafers. From Fig. 3 one can see that the results obtained from SIRM are systematically less than the values obtained from IR-LST when the density of precipitates, determined by IR-LST, exceeds 108 cm 3. We assume that this difference is caused by a relatively low sensitivity of SIRM in the case of small size precipitates. So we have used IR-LST as the main
method in order to receive a more complete picture of precipitation. The distribution of precipitates along wafers containing various levels of N doping is presented in Fig. 4. SIRM data were collected from a depth of 60–120 mm, whereas IR-LST data were obtained from the depth of 300–600 mm. Solid symbols and solid lines correspond to IR-LST, open symbols and dashed lines correspond to SIRM. It can be seen that for the annealed HN material a nearly uniform radial distribution of precipitates is formed. The absolute value of concentration of precipitates exceeds 109 cm 3 for almost all radial
6
10
7
10
8
10
9
10
10
10
IR - LST density + 4.3.106 (cm-3)
V.D. Akhmetov et al. / Materials Science in Semiconductor Processing 5 (2003) 391–396
394
positions. This high density of precipitates allows one to expect a good quality of the intrinsic gettering capability. If the LN material is used a high density of
70
Denuded Zone (µm)
60
50
40
30
20
10 0
20
40
60
80
100
120
140
Distance from Wafer Edge (mm)
Fig. 5. Radial distribution of denuded zone in nitrogen-doped annealed wafers. Upper curve—LN wafer, 12001C, 2 h; lower curve—HN wafer, 12001C, 2 h.
precipitates was reliably formed only in the inner part of the wafer, between center and approximately middle of the radius. Large non-uniformities in the density of precipitates were observed in the outer part of the LN wafers. The detected BMD density varies from 5 106 to 6 108 atoms/cm3. The observed fluctuating behavior of precipitates by changing the N content can be explained in the following manner: for oxygen concentrations of 5– 6.3 1017 atoms/cm3—as present for LN and HN wafers—the precipitation of oxygen proceeds slowly. Adding of N on the LN level enhances the precipitation, but the effect of N is more pronounced in the central part of the wafer where vacancy-type defects dominate. This is expected because both factors, V and N, stimulate oxide precipitation [2,6]. By choosing an appropriate level of N doping (=HN material) it is possible to enhance drastically the oxide precipitation in all wafer parts. The radial distribution of the denuded zone in LN and HN annealed wafers is depicted in Fig. 5. It can be seen that the width of DZ decreases from 50–70 to 15–40 mm with increasing N content. There is a tendency of
Fig. 6. IR-LST cross section of low nitrogen-doped silicon wafer after 12001C, 2 h.
V.D. Akhmetov et al. / Materials Science in Semiconductor Processing 5 (2003) 391–396
395
Fig. 7. IR-LST cross section of high nitrogen-doped silicon wafer after 12001C, 2 h.
narrowing of the denuded zone in the outer part of wafer. But in all cases the width of the denuded zone exceeds 12 mm. That seems to be enough for the formation of active layers for most integrated circuits. Typical IR-LST images from cross sectioned wafers including the denuded zone region are presented in Figs. 6 and 7 (LN and HN material, respectively). These images demonstrate the existence of the defect-free denuded zone in both types of materials. Light points correspond to oxide precipitates. The warped line of the silicon–air interface instead of a straight one as well as some large elongated light areas are caused by parasitic scattering from a not ideal angle between planar and cross sectioned surfaces. 4. Conclusion The radial distribution of oxide precipitates as well as the properties of the denuded zone formed in annealed (12001C) 300 mm nitrogen-doped CZ-Si wafers were investigated by means of light scattering methods. Two main results were obtained: 1. The addition of N enhances the density of oxide precipitates and improves the homogeneity of its
distribution especially in the peripheral part of the silicon wafer. Nearly uniform radial profiles of oxide precipitates can be achieved with a range of precipitation density: 1–3 109 cm 3. 2. The width of the denuded zone tends to narrow with increase N doping but remains more than 12 mm across the entire wafer. The obtained results show that annealing of high nitrogen-doped silicon wafers yield a high density of relatively uniform distributed oxide precipitates in the depth over the entire wafer. It leads to the formation of a denuded zone which is sufficiently wide for device applications. Therefore, these results describe a suitable way to achieve an activated intrinsic getter for argon annealed 300 mm silicon wafers.
Acknowledgements This work was supported by the Federal Department of Education and Research of the FRG under contract number 01 M 2973A. The authors alone are responsible for the content.
396
V.D. Akhmetov et al. / Materials Science in Semiconductor Processing 5 (2003) 391–396
References [1] Goto H, Tanaka M, Pan L-S, Kashima K. Jpn J Appl Phys Part 1 2001;40:3944. [2] Sueoka K, Akatsuka M, Yonemura M, Ono T, Eiichi Asayama, Koike Y, Sadamitsu S, GADEST 2001 on Solid State Phenomena, vol. 82–84, 2002. p. 49. . R, Virbulis J, Dornberger E, Schmolke [3] Ammon Wv, Holzl R, Gr.af D. J Cryst Growth 2002;226:19.
[4] Karoui A, Karouri FS, Rozgonyi GA, Hourai M, Sueoka K. Semiconductor Silicon 2002, ECS Proceedings, vol. 2002-2, 2002. p. 670. [5] Muller . T, Siebert W, Messmann K, Walich R, Krottentha. R, Ikari A, Ammon Wv, Semiconductor Silicon ler P, Holz 2002, ECS Proceedings, vol. 2002-2, 2002. p. 194. [6] Voronkov VV, Falster R. J Appl Phys 2002;91:5802.