Charged particle beam devices and membrane assemblies useful therein

A membrane assembly comprising:

• a pressure-sealing membrane suitable for separating a first-pressure environment from a second-pressure environment, said second-pressure environment having a different pressure to said first-pressure environment, said pressure-sealing membrane having a thickness of less than 20 nanometers and being substantially transparent to electrons;
• a supporting membrane layer being formed with a cornerless aperture having a longest chord of at least 100.000 nanometers, said pressure-sealing membrane being bonded to said supporting membrane layer;
• and
• a holding frame being formed with a second aperture larger than and overlying said cornerless aperture.

A charged particle beam device, comprising:

• a charged particle beam source situated in a first-pressure environment;
• a region transparent to a charged particle beam from said charged particle beam source;
• a sample support operative to support a sample, said sample support and said sample situated in a second-pressure environment, said second-pressure environment being at a higher pressure than said first-pressure environment and said second-pressure environment being at atmospheric pressure;
• a membrane assembly separating said second-pressure environment from said first-pressure environment, said membrane assembly comprising:
• a pressure-sealing membrane being substantially transparent to a charged particle beam from said charged particle beam source;
• a supporting membrane layer being formed with a cornerless aperture having a longest chord of at least 100,000 nanometers, and said pressure-sealing membrane being bonded to said supporting membrane layer;
• and
• a holding frame being formed with a second aperture larger than and overlying said cornerless aperture;
• and
• an electron-detecting subassembly situated in said second-pressure environment, said electron-detecting subassembly comprising at least two metal lines each defining a shape, said shapes being mutually spaced and mutually nested, for detection of electrons.