one more thing, I'm not sure if the background check you mentioned means "police certificate" that should be sent if you have lived in any country for more than 6 months. If we aren't talking about the same thing, I think you have to look for more info about your inquiry. This is some info about police certificate:
When you apply to become a permanent resident of Canada, you and your *family members, if applicable, must provide a police certificate, clearance or record of no information for each country you lived in for more than six months in the last 10 years. If you, or your family members, were under 18 years of age when you lived in one of those countries, you do not need to provide a police certificate for that country. Please visit our Web site for specific instructions on how to get a police certificate for each country. If you cannot get police certificates, you must send a written explanation with your application and an original letter from the police authorities confirming that they will not issue a certificate.
Some countries may ask you to provide fingerprints, photos or a letter from Canadian immigration authorities explaining why you need a police certificate. Your local police or the Royal Canadian Mounted Police (RCMP) may be able to tell you where you can get fingerprints taken. You do not need to send Citizenship and Immigration Canada a set of fingerprints when you submit your application, unless it is specifically requested in the instruction Guide that comes with your application kit. For all permanent residence applications processed inside Canada at the Case Processing Centre in Vegreville, Alberta, a police certificate for Canada is not required.
Please note that for some countries, you should not get police certificates before applying for immigration; those countries are listed in the instruction Guide that comes with your application kit. In addition, if the police certificate is not English or French, you must also submit a certified translation from a professional translator.
*A family member is a spouse, common-law partner, dependant child or dependant child of a dependant child.
The Internet links below will provide you with more detailed information:
Description: How to obtain a police certificate
Description: Fingerprints Request Letter (Adobe® Acrobat Reader required)
Description: Request for Police Certificates/Clearances and Authorization for Release of Information (Adobe® Acrobat Reader required)